Merge.

33 files changed, 541 insertions, 173 deletions

diff --git a/src/c/cgi.c b/src/c/cgi.c
index 539b83c2..d060532c 100644
--- a/src/c/cgi.c
+++ b/src/c/cgi.c
@@ -60,8 +60,10 @@ static void log_error(void *data, const char *fmt, ...) {
 static void log_debug(void *data, const char *fmt, ...) {
 }
 
+static uw_loggers ls = {NULL, log_error, log_debug};
+
 int main(int argc, char *argv[]) {
-  uw_context ctx = uw_request_new_context(0, &uw_application, NULL, log_error, log_debug);
+  uw_context ctx = uw_request_new_context(0, &uw_application, &ls);
   uw_request_context rc = uw_new_request_context();
   request_result rr;
   char *method = getenv("REQUEST_METHOD"),
@@ -108,7 +110,7 @@ int main(int argc, char *argv[]) {
   uw_set_on_success("");
   uw_set_headers(ctx, get_header, NULL);
   uw_set_env(ctx, get_env, NULL);
-  uw_request_init(&uw_application, NULL, log_error, log_debug);
+  uw_request_init(&uw_application, &ls);
 
   body[body_pos] = 0;
   rr = uw_request(rc, ctx, method, path, query_string, body, body_pos,
diff --git a/src/c/fastcgi.c b/src/c/fastcgi.c
index 5c80d3ae..f3e66e3a 100644
--- a/src/c/fastcgi.c
+++ b/src/c/fastcgi.c
@@ -324,7 +324,8 @@ int fastcgi_send_normal(int sock, const void *buf, ssize_t len) {
 static void *worker(void *data) {
   FCGI_Input *in = fastcgi_input();
   FCGI_Output *out = fastcgi_output();
-  uw_context ctx = uw_request_new_context(*(int *)data, &uw_application, out, log_error, log_debug);
+  uw_loggers ls = {out, log_error, log_debug};
+  uw_context ctx = uw_request_new_context(*(int *)data, &uw_application, &ls);
   uw_request_context rc = uw_new_request_context();
   headers hs;
   size_t body_size = 0;
@@ -514,7 +515,7 @@ static void sigint(int signum) {
   exit(0);
 }
 
-static loggers ls = {&uw_application, NULL, log_error, log_debug};
+static uw_loggers ls = {NULL, log_error, log_debug};
 
 int main(int argc, char *argv[]) {
   // The skeleton for this function comes from Beej's sockets tutorial.
@@ -563,7 +564,7 @@ int main(int argc, char *argv[]) {
   }
 
   uw_set_on_success("");
-  uw_request_init(&uw_application, NULL, log_error, log_debug);
+  uw_request_init(&uw_application, &ls);
 
   names = calloc(nthreads, sizeof(int));
 
@@ -572,7 +573,11 @@ int main(int argc, char *argv[]) {
   {
     pthread_t thread;
 
-    if (pthread_create_big(&thread, NULL, client_pruner, &ls)) {
+    pruner_data *pd = (pruner_data *)malloc(sizeof(pruner_data));
+    pd->app = &uw_application;
+    pd->loggers = &ls;
+
+    if (pthread_create_big(&thread, NULL, client_pruner, pd)) {
       fprintf(stderr, "Error creating pruner thread\n");
       return 1;
     }
diff --git a/src/c/http.c b/src/c/http.c
index 25d2a320..32dd1dd1 100644
--- a/src/c/http.c
+++ b/src/c/http.c
@@ -70,9 +70,11 @@ static void log_debug(void *data, const char *fmt, ...) {
   }
 }
 
+static uw_loggers ls = {NULL, log_error, log_debug};
+
 static void *worker(void *data) {
   int me = *(int *)data;
-  uw_context ctx = uw_request_new_context(me, &uw_application, NULL, log_error, log_debug);
+  uw_context ctx = uw_request_new_context(me, &uw_application, &ls);
   size_t buf_size = 1024;
   char *buf = malloc(buf_size), *back = buf;
   uw_request_context rc = uw_new_request_context();
@@ -307,8 +309,6 @@ static void sigint(int signum) {
   exit(0);
 }
 
-static loggers ls = {&uw_application, NULL, log_error, log_debug};
-
 int main(int argc, char *argv[]) {
   // The skeleton for this function comes from Beej's sockets tutorial.
   int sockfd;  // listen on sock_fd
@@ -374,7 +374,7 @@ int main(int argc, char *argv[]) {
     }
   }
 
-  uw_request_init(&uw_application, NULL, log_error, log_debug);
+  uw_request_init(&uw_application, &ls);
 
   names = calloc(nthreads, sizeof(int));
 
@@ -411,7 +411,11 @@ int main(int argc, char *argv[]) {
   {
     pthread_t thread;
 
-    if (pthread_create_big(&thread, NULL, client_pruner, &ls)) {
+    pruner_data *pd = (pruner_data *)malloc(sizeof(pruner_data));
+    pd->app = &uw_application;
+    pd->loggers = &ls;
+
+    if (pthread_create_big(&thread, NULL, client_pruner, pd)) {
       fprintf(stderr, "Error creating pruner thread\n");
       return 1;
     }
diff --git a/src/c/request.c b/src/c/request.c
index b925cc3c..813d967c 100644
--- a/src/c/request.c
+++ b/src/c/request.c
@@ -12,6 +12,7 @@
 #include <pthread.h>
 
 #include "urweb.h"
+#include "request.h"
 
 #define MAX_RETRIES 5
 
@@ -32,8 +33,11 @@ static int try_rollback(uw_context ctx, int will_retry, void *logger_data, uw_lo
   return r;
 }
 
-uw_context uw_request_new_context(int id, uw_app *app, void *logger_data, uw_logger log_error, uw_logger log_debug) {
-  uw_context ctx = uw_init(id, logger_data, log_debug);
+uw_context uw_request_new_context(int id, uw_app *app, uw_loggers *ls) {
+  void *logger_data = ls->logger_data;
+  uw_logger log_debug = ls->log_debug;
+  uw_logger log_error = ls->log_error;
+  uw_context ctx = uw_init(id, ls);
   int retries_left = MAX_RETRIES;
   uw_set_app(ctx, app);
 
@@ -78,20 +82,15 @@ static void *ticker(void *data) {
 }
 
 typedef struct {
-  uw_app *app;
-  void *logger_data;
-  uw_logger log_error, log_debug;
-} loggers;
-
-typedef struct {
   int id;
-  loggers *ls;
+  uw_loggers *ls;
   uw_periodic pdic;
+  uw_app *app;
 } periodic;
 
 static void *periodic_loop(void *data) {
   periodic *p = (periodic *)data;
-  uw_context ctx = uw_request_new_context(p->id, p->ls->app, p->ls->logger_data, p->ls->log_error, p->ls->log_debug);
+  uw_context ctx = uw_request_new_context(p->id, p->app, p->ls);
 
   if (!ctx)
     exit(1);
@@ -145,14 +144,17 @@ int pthread_create_big(pthread_t *outThread, void *foo, void *threadFunc, void *
   }
 }
 
-void uw_request_init(uw_app *app, void *logger_data, uw_logger log_error, uw_logger log_debug) {
+void uw_request_init(uw_app *app, uw_loggers* ls) {
   uw_context ctx;
   failure_kind fk;
   uw_periodic *ps;
-  loggers *ls = malloc(sizeof(loggers));
   int id;
   char *stackSize_s;
 
+  uw_logger log_debug = ls->log_debug;
+  uw_logger log_error = ls->log_error;
+  void* logger_data = ls->logger_data;
+
   if ((stackSize_s = getenv("URWEB_STACK_SIZE")) != NULL && stackSize_s[0] != 0) {
     stackSize = atoll(stackSize_s);
 
@@ -162,11 +164,6 @@ void uw_request_init(uw_app *app, void *logger_data, uw_logger log_error, uw_log
     }
   }
 
-  ls->app = app;
-  ls->logger_data = logger_data;
-  ls->log_error = log_error;
-  ls->log_debug = log_debug;
-
   uw_global_init();
   uw_app_init(app);
 
@@ -179,7 +176,7 @@ void uw_request_init(uw_app *app, void *logger_data, uw_logger log_error, uw_log
     }
   }
 
-  ctx = uw_request_new_context(0, app, logger_data, log_error, log_debug);
+  ctx = uw_request_new_context(0, app, ls);
 
   if (!ctx)
     exit(1);
@@ -205,6 +202,7 @@ void uw_request_init(uw_app *app, void *logger_data, uw_logger log_error, uw_log
     arg->id = id++;
     arg->ls = ls;
     arg->pdic = *ps;
+    arg->app = app;
     
     if (pthread_create_big(&thread, NULL, periodic_loop, arg)) {
       fprintf(stderr, "Error creating periodic thread\n");
@@ -240,7 +238,7 @@ request_result uw_request(uw_request_context rc, uw_context ctx,
                           void (*on_success)(uw_context), void (*on_failure)(uw_context),
                           void *logger_data, uw_logger log_error, uw_logger log_debug,
                           int sock,
-                          int (*send)(int sockfd, const void *buf, size_t len),
+                          int (*send)(int sockfd, const void *buf, ssize_t len),
                           int (*close)(int fd)) {
   int retries_left = MAX_RETRIES;
   failure_kind fk;
@@ -588,8 +586,8 @@ request_result uw_request(uw_request_context rc, uw_context ctx,
 }
 
 void *client_pruner(void *data) {
-  loggers *ls = (loggers *)data;
-  uw_context ctx = uw_request_new_context(0, ls->app, ls->logger_data, ls->log_error, ls->log_debug);
+  pruner_data *pd = (pruner_data *)data;
+  uw_context ctx = uw_request_new_context(0, pd->app, pd->loggers);
 
   if (!ctx)
     exit(1);
diff --git a/src/c/static.c b/src/c/static.c
index 80ea5387..8f35a2d4 100644
--- a/src/c/static.c
+++ b/src/c/static.c
@@ -7,13 +7,15 @@
 
 extern uw_app uw_application;
 
-static void log_debug(void *data, const char *fmt, ...) {
+static void log_(void *data, const char *fmt, ...) {
   va_list ap;
   va_start(ap, fmt);
 
   vprintf(fmt, ap);
 }
 
+static uw_loggers loggers = {NULL, log_, log_};
+
 int main(int argc, char *argv[]) {
   uw_context ctx;
   failure_kind fk;
@@ -23,7 +25,7 @@ int main(int argc, char *argv[]) {
     return 1;
   }
  
-  ctx = uw_init(0, NULL, log_debug);
+  ctx = uw_init(0, &loggers);
   uw_set_app(ctx, &uw_application);
   uw_initialize(ctx);
 
diff --git a/src/c/urweb.c b/src/c/urweb.c
index d4c0b439..78afcd05 100644
--- a/src/c/urweb.c
+++ b/src/c/urweb.c
@@ -460,8 +460,7 @@ struct uw_context {
 
   void *client_data;
 
-  void *logger_data;
-  uw_logger log_debug;
+  uw_loggers *loggers;
 
   int isPost, hasPostBody;
   uw_Basis_postBody postBody;
@@ -487,7 +486,7 @@ size_t uw_page_max = SIZE_MAX;
 size_t uw_heap_max = SIZE_MAX;
 size_t uw_script_max = SIZE_MAX;
 
-uw_context uw_init(int id, void *logger_data, uw_logger log_debug) {
+uw_context uw_init(int id, uw_loggers *lg) {
   uw_context ctx = malloc(sizeof(struct uw_context));
 
   ctx->app = NULL;
@@ -546,8 +545,7 @@ uw_context uw_init(int id, void *logger_data, uw_logger log_debug) {
 
   ctx->client_data = uw_init_client_data();
 
-  ctx->logger_data = logger_data;
-  ctx->log_debug = log_debug;
+  ctx->loggers = lg;
 
   ctx->isPost = ctx->hasPostBody = 0;
 
@@ -601,6 +599,11 @@ void *uw_get_db(uw_context ctx) {
   return ctx->db;
 }
 
+
+uw_loggers* uw_get_loggers(struct uw_context *ctx) {
+  return ctx->loggers;
+}
+
 void uw_free(uw_context ctx) {
   size_t i;
 
@@ -1258,17 +1261,34 @@ void uw_end_initializing(uw_context ctx) {
   ctx->amInitializing = 0;
 }
 
+static void align_heap(uw_context ctx) {
+  size_t posn = ctx->heap.front - ctx->heap.start;
+
+  if (posn % 4 != 0) {
+    size_t bump = 4 - posn % 4;
+    uw_check_heap(ctx, bump);
+    ctx->heap.front += bump;
+  }
+}
+
 void *uw_malloc(uw_context ctx, size_t len) {
+  // On some architectures, it's important that all word-sized memory accesses
+  // be to word-aligned addresses, so we'll do a little bit of extra work here
+  // in anticipation of a possible word-aligned access to the address we'll
+  // return.
+
   void *result;
 
   if (ctx->amInitializing) {
-    result = malloc(len);
+    int error = posix_memalign(&result, 4, len);
 
-    if (result)
+    if (!error)
       return result;
     else
-      uw_error(ctx, FATAL, "uw_malloc: malloc() returns 0");
+      uw_error(ctx, FATAL, "uw_malloc: posix_memalign() returns %d", error);
   } else {
+    align_heap(ctx);
+
     uw_check_heap(ctx, len);
 
     result = ctx->heap.front;
@@ -1278,6 +1298,8 @@ void *uw_malloc(uw_context ctx, size_t len) {
 }
 
 void uw_begin_region(uw_context ctx) {
+  align_heap(ctx);
+
   regions *r = (regions *) ctx->heap.front;
 
   uw_check_heap(ctx, sizeof(regions));
@@ -1588,6 +1610,9 @@ uw_Basis_source uw_Basis_new_client_source(uw_context ctx, uw_Basis_string s) {
   int len;
   size_t s_len = strlen(s);
 
+  if(ctx->id < 0)
+    uw_error(ctx, FATAL, "Attempt to create client source using inappropriate context");
+
   uw_check_script(ctx, 15 + 2 * INTS_MAX + s_len);
   sprintf(ctx->script.front, "s%d_%llu=sc(exec(%n", ctx->id, ctx->source_count, &len);
   ctx->script.front += len;
@@ -3316,32 +3341,58 @@ int uw_commit(uw_context ctx) {
         }
       }
 
-  for (i = ctx->used_transactionals-1; i >= 0; --i)
-    if (ctx->transactionals[i].rollback == NULL)
-      if (ctx->transactionals[i].commit) {
-        ctx->transactionals[i].commit(ctx->transactionals[i].data);
-        if (uw_has_error(ctx)) {
-          uw_rollback(ctx, 0);
-          return 0;
-        }
-      }
-
   if (ctx->transaction_started) {
     int code = ctx->app->db_commit(ctx);
 
     if (code) {
-      if (code == -1)
+      if (ctx->client)
+        release_client(ctx->client);
+
+      if (code == -1) {
+        // This case is for a serialization failure, which is not really an "error."
+        // The transaction will restart, so we should rollback any transactionals
+        // that triggered above.
+
+        for (i = ctx->used_transactionals-1; i >= 0; --i)
+          if (ctx->transactionals[i].rollback != NULL)
+            ctx->transactionals[i].rollback(ctx->transactionals[i].data);
+
+        for (i = ctx->used_transactionals-1; i >= 0; --i)
+          if (ctx->transactionals[i].free)
+            ctx->transactionals[i].free(ctx->transactionals[i].data, 1);
+
 	return 1;
+      }
 
       for (i = ctx->used_transactionals-1; i >= 0; --i)
-	if (ctx->transactionals[i].free)
-	  ctx->transactionals[i].free(ctx->transactionals[i].data, 0);
+        if (ctx->transactionals[i].free)
+          ctx->transactionals[i].free(ctx->transactionals[i].data, 0);
 
       uw_set_error_message(ctx, "Error running SQL COMMIT");
       return 0;
     }
   }
 
+  for (i = ctx->used_transactionals-1; i >= 0; --i)
+    if (ctx->transactionals[i].rollback == NULL)
+      if (ctx->transactionals[i].commit) {
+        ctx->transactionals[i].commit(ctx->transactionals[i].data);
+        if (uw_has_error(ctx)) {
+           if (ctx->client)
+             release_client(ctx->client);
+
+           for (i = ctx->used_transactionals-1; i >= 0; --i)
+             if (ctx->transactionals[i].rollback != NULL)
+               ctx->transactionals[i].rollback(ctx->transactionals[i].data);
+
+           for (i = ctx->used_transactionals-1; i >= 0; --i)
+             if (ctx->transactionals[i].free)
+               ctx->transactionals[i].free(ctx->transactionals[i].data, 0);
+
+          return 0;
+        }
+      }
+
   for (i = 0; i < ctx->used_deltas; ++i) {
     delta *d = &ctx->deltas[i];
     client *c = find_client(d->client);
@@ -3455,11 +3506,12 @@ int uw_commit(uw_context ctx) {
 
 size_t uw_transactionals_max = SIZE_MAX;
 
-void uw_register_transactional(uw_context ctx, void *data, uw_callback commit, uw_callback rollback,
+int uw_register_transactional(uw_context ctx, void *data, uw_callback commit, uw_callback rollback,
                                uw_callback_with_retry free) {
   if (ctx->used_transactionals >= ctx->n_transactionals) {
     if (ctx->used_transactionals+1 > uw_transactionals_max)
-      uw_error(ctx, FATAL, "Exceeded limit on number of transactionals");
+      // Exceeded limit on number of transactionals.
+      return -1;
     ctx->transactionals = realloc(ctx->transactionals, sizeof(transactional) * (ctx->used_transactionals+1));
     ++ctx->n_transactionals;
   }
@@ -3468,6 +3520,8 @@ void uw_register_transactional(uw_context ctx, void *data, uw_callback commit, u
   ctx->transactionals[ctx->used_transactionals].commit = commit;
   ctx->transactionals[ctx->used_transactionals].rollback = rollback;
   ctx->transactionals[ctx->used_transactionals++].free = free;
+
+  return 0;
 }
 
 
@@ -3965,7 +4019,8 @@ uw_Basis_int uw_Basis_toSeconds(uw_context ctx, uw_Basis_time tm) {
 
 uw_Basis_time uw_Basis_fromDatetime(uw_context ctx, uw_Basis_int year, uw_Basis_int month, uw_Basis_int day, uw_Basis_int hour, uw_Basis_int minute, uw_Basis_int second) {
   struct tm tm = { .tm_year = year - 1900, .tm_mon = month, .tm_mday = day,
-                   .tm_hour = hour, .tm_min = minute, .tm_sec = second };
+                   .tm_hour = hour, .tm_min = minute, .tm_sec = second,
+                   .tm_isdst = -1 };
   uw_Basis_time r = { timelocal(&tm) };
   return r;
 }
@@ -4136,8 +4191,8 @@ uw_Basis_int uw_Basis_naughtyDebug(uw_context ctx, uw_Basis_string s) {
 }
 
 uw_Basis_unit uw_Basis_debug(uw_context ctx, uw_Basis_string s) {
-  if (ctx->log_debug)
-    ctx->log_debug(ctx->logger_data, "%s\n", s);
+  if (ctx->loggers->log_debug)
+    ctx->loggers->log_debug(ctx->loggers->logger_data, "%s\n", s);
   else
     fprintf(stderr, "%s\n", s);
   return uw_unit_v;
@@ -4379,3 +4434,13 @@ uw_Basis_postField *uw_Basis_firstFormField(uw_context ctx, uw_Basis_string s) {
 
   return f;
 }
+
+uw_Basis_string uw_Basis_blessData(uw_context ctx, uw_Basis_string s) {
+  char *p = s;
+
+  for (; *p; ++p)
+    if (!isalnum(*p) && *p != '-' && *p != '_')
+      uw_error(ctx, FATAL, "Illegal HTML5 data-* attribute: %s", s);
+
+  return s;
+}
diff --git a/src/compiler.sml b/src/compiler.sml
index 37272758..fd143485 100644
--- a/src/compiler.sml
+++ b/src/compiler.sml
@@ -874,6 +874,7 @@ fun parseUrp' accLibs fname =
                                    | "timeFormat" => Settings.setTimeFormat arg
                                    | "noMangleSql" => Settings.setMangleSql false
                                    | "html5" => Settings.setIsHtml5 true
+                                   | "lessSafeFfi" => Settings.setLessSafeFfi true
 
                                    | _ => ErrorMsg.error ("Unrecognized command '" ^ cmd ^ "'");
                                  read ()
diff --git a/src/corify.sml b/src/corify.sml
index 085b2eb8..b08ef7eb 100644
--- a/src/corify.sml
+++ b/src/corify.sml
@@ -643,6 +643,12 @@ fun corifyExp st (e, loc) =
 
       | L.ELet (x, t, e1, e2) => (L'.ELet (x, corifyCon st t, corifyExp st e1, corifyExp st e2), loc)
 
+fun isTransactional (c, _) =
+    case c of
+        L'.TFun (_, c) => isTransactional c
+      | L'.CApp ((L'.CFfi ("Basis", "transaction"), _), _) => true
+      | _ => false
+
 fun corifyDecl mods (all as (d, loc : EM.span), st) =
     case d of
         L.DCon (x, n, k, c) =>
@@ -970,12 +976,6 @@ fun corifyDecl mods (all as (d, loc : EM.span), st) =
                                                in
                                                    transactify c
                                                end
-
-                                       fun isTransactional (c, _) =
-                                           case c of
-                                               L'.TFun (_, c) => isTransactional c
-                                             | L'.CApp ((L'.CFfi ("Basis", "transaction"), _), _) => true
-                                             | _ => false
                                    in
                                        if isTransactional c then
                                            let
@@ -1164,6 +1164,66 @@ fun corifyDecl mods (all as (d, loc : EM.span), st) =
                       ([], st))
         end
 
+      | L.DFfi (x, n, modes, t) =>
+        let
+            val m = case St.name st of
+                        [m] => m
+                      | _ => (ErrorMsg.errorAt loc "Used 'ffi' declaration beneath module top level";
+                              "")
+
+            val name = (m, x)
+
+            val (st, n) = St.bindVal st x n
+            val s = doRestify Settings.Url (mods, x)
+
+            val t' = corifyCon st t
+
+            fun numArgs (t : L'.con) =
+                case #1 t of
+                    L'.TFun (_, ran) => 1 + numArgs ran
+                  | _ => 0
+
+            fun makeArgs (i, t : L'.con, acc) =
+                case #1 t of
+                    L'.TFun (dom, ran) => makeArgs (i-1, ran, ((L'.ERel i, loc), dom) :: acc)
+                  | _ => rev acc
+
+            fun wrapAbs (i, t : L'.con, tTrans, e) =
+                case (#1 t, #1 tTrans) of
+                    (L'.TFun (dom, ran), L'.TFun (_, ran')) => (L'.EAbs ("x" ^ Int.toString i, dom, ran, wrapAbs (i+1, ran, ran', e)), loc)
+                  | _ => e
+
+            fun getRan (t : L'.con) =
+                case #1 t of
+                    L'.TFun (_, ran) => getRan ran
+                  | _ => t
+
+            fun addLastBit (t : L'.con) =
+                case #1 t of
+                    L'.TFun (dom, ran) => (L'.TFun (dom, addLastBit ran), #2 t)
+                  | _ => (L'.TFun ((L'.TRecord (L'.CRecord ((L'.KType, loc), []), loc), loc), t), loc)
+
+            val e = (L'.EFfiApp (m, x, makeArgs (numArgs t' - 1, t', [])), loc)
+            val (e, tTrans) = if isTransactional t' then
+                                  ((L'.EAbs ("_", (L'.TRecord (L'.CRecord ((L'.KType, loc), []), loc), loc), getRan t', e), loc), addLastBit t')
+                              else
+                                  (e, t')
+            val e = wrapAbs (0, t', tTrans, e)
+        in
+            app (fn Source.Effectful => Settings.addEffectful name
+                  | Source.BenignEffectful => Settings.addBenignEffectful name
+                  | Source.ClientOnly => Settings.addClientOnly name
+                  | Source.ServerOnly => Settings.addServerOnly name
+                  | Source.JsFunc s => Settings.addJsFunc (name, s)) modes;
+
+            if isTransactional t' andalso not (Settings.isBenignEffectful name) then
+                Settings.addEffectful name
+            else
+                ();
+
+            ([(L'.DVal (x, n, t', e, s), loc)], st)
+        end
+
 and corifyStr mods ((str, loc), st) =
     case str of
         L.StrConst ds =>
@@ -1237,7 +1297,8 @@ fun maxName ds = foldl (fn ((d, _), n) =>
                              | L.DStyle (_, _, n') => Int.max (n, n')
                              | L.DTask _ => n
                              | L.DPolicy _ => n
-                             | L.DOnError _ => n)
+                             | L.DOnError _ => n
+                             | L.DFfi (_, n', _, _) => Int.max (n, n'))
                        0 ds
 
 and maxNameStr (str, _) =
diff --git a/src/elab.sml b/src/elab.sml
index 2dab5c34..249531f1 100644
--- a/src/elab.sml
+++ b/src/elab.sml
@@ -1,4 +1,4 @@
-(* Copyright (c) 2008-2011, Adam Chlipala
+(* Copyright (c) 2008-2011, 2014, Adam Chlipala
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -181,6 +181,7 @@ datatype decl' =
        | DTask of exp * exp
        | DPolicy of exp
        | DOnError of int * string list * string
+       | DFfi of string * int * Source.ffi_mode list * con
 
      and str' =
          StrConst of decl list
diff --git a/src/elab_env.sml b/src/elab_env.sml
index 465fb7e4..9fbe7bd7 100644
--- a/src/elab_env.sml
+++ b/src/elab_env.sml
@@ -1681,5 +1681,6 @@ fun declBinds env (d, loc) =
       | DTask _ => env
       | DPolicy _ => env
       | DOnError _ => env
+      | DFfi (x, n, _, t) => pushENamedAs env x n t
 
 end
diff --git a/src/elab_err.sig b/src/elab_err.sig
index b5e3d64d..acf137df 100644
--- a/src/elab_err.sig
+++ b/src/elab_err.sig
@@ -81,6 +81,7 @@ signature ELAB_ERR = sig
            | Unresolvable of ErrorMsg.span * Elab.con
            | OutOfContext of ErrorMsg.span * (Elab.exp * Elab.con) option
            | IllegalRec of string * Elab.exp
+           | IllegalFlex of Source.exp
 
     val expError : ElabEnv.env -> exp_error -> unit
 
diff --git a/src/elab_err.sml b/src/elab_err.sml
index 4754d4ce..33daa118 100644
--- a/src/elab_err.sml
+++ b/src/elab_err.sml
@@ -180,6 +180,7 @@ datatype exp_error =
      | Unresolvable of ErrorMsg.span * con
      | OutOfContext of ErrorMsg.span * (exp * con) option
      | IllegalRec of string * exp
+     | IllegalFlex of Source.exp
 
 val simplExp = U.Exp.mapB {kind = fn _ => fn k => k,
                            con = fn env => fn c => #1 (ElabOps.reduceCon env (c, ErrorMsg.dummySpan)),
@@ -251,6 +252,9 @@ fun expError env err =
         (ErrorMsg.errorAt (#2 e) "Illegal 'val rec' righthand side (must be a function abstraction)";
          eprefaces' [("Variable", PD.string x),
                      ("Expression", p_exp env e)])
+      | IllegalFlex e =>
+        (ErrorMsg.errorAt (#2 e) "Flex record syntax (\"...\") only allowed in patterns";
+         eprefaces' [("Expression", SourcePrint.p_exp e)])
 
 
 datatype decl_error =
diff --git a/src/elab_print.sml b/src/elab_print.sml
index 7ce94c97..957d4646 100644
--- a/src/elab_print.sml
+++ b/src/elab_print.sml
@@ -852,6 +852,7 @@ fun p_decl env (dAll as (d, _) : decl) =
                            space,
                            p_exp env e1]
       | DOnError _ => string "ONERROR"
+      | DFfi _ => string "FFI"
 
 and p_str env (str, _) =
     case str of
diff --git a/src/elab_util.sml b/src/elab_util.sml
index 60245585..fef55852 100644
--- a/src/elab_util.sml
+++ b/src/elab_util.sml
@@ -927,7 +927,8 @@ fun mapfoldB {kind = fk, con = fc, exp = fe, sgn_item = fsgi, sgn = fsg, str = f
                                                    bind (ctx, NamedE (x, (CModProj (n, [], "css_class"), loc)))
                                                  | DTask _ => ctx
                                                  | DPolicy _ => ctx
-                                                 | DOnError _ => ctx,
+                                                 | DOnError _ => ctx
+                                                 | DFfi (x, _, _, t) => bind (ctx, NamedE (x, t)),
                                                mfd ctx d)) ctx ds,
                      fn ds' => (StrConst ds', loc))
               | StrVar _ => S.return2 strAll
@@ -1056,6 +1057,10 @@ fun mapfoldB {kind = fk, con = fc, exp = fe, sgn_item = fsgi, sgn = fsg, str = f
                      fn e1' =>
                         (DPolicy e1', loc))
               | DOnError _ => S.return2 dAll
+              | DFfi (x, n, modes, t) =>
+                S.map2 (mfc ctx t,
+                        fn t' =>
+                           (DFfi (x, n, modes, t'), loc))
 
         and mfvi ctx (x, n, c, e) =
             S.bind2 (mfc ctx c,
@@ -1234,6 +1239,7 @@ and maxNameDecl (d, _) =
       | DTask _ => 0
       | DPolicy _ => 0
       | DOnError _ => 0
+      | DFfi (_, n, _, _) => n
 and maxNameStr (str, _) =
     case str of
         StrConst ds => maxName ds
diff --git a/src/elaborate.sml b/src/elaborate.sml
index 5dd86f18..d492883f 100644
--- a/src/elaborate.sml
+++ b/src/elaborate.sml
@@ -2183,8 +2183,13 @@ fun elabExp (env, denv) (eAll as (e, loc)) =
                 (e', (#1 (chaseUnifs t'), loc), enD gs2 @ gs1)
             end
 
-          | L.ERecord xes =>
+          | L.ERecord (xes, flex) =>
             let
+                val () = if flex then
+                             expError env (IllegalFlex eAll)
+                         else
+                             ()
+
                 val (xes', gs) = ListUtil.foldlMap (fn ((x, e), gs) =>
                                                        let
                                                            val (x', xk, gs1) = elabCon (env, denv) x
@@ -2994,6 +2999,7 @@ and sgiOfDecl (d, loc) =
       | L'.DTask _ => []
       | L'.DPolicy _ => []
       | L'.DOnError _ => []
+      | L'.DFfi (x, n, _, t) => [(L'.SgiVal (x, n, t), loc)]
 
 and subSgn' counterparts env strLoc sgn1 (sgn2 as (_, loc2)) =
     ((*prefaces "subSgn" [("sgn1", p_sgn env sgn1),
@@ -4293,6 +4299,20 @@ and elabDecl (dAll as (d, loc), (env, denv, gs)) =
                          ([(L'.DOnError (n, ms, s), loc)], (env, denv, gs))
                      end)
 
+              | L.DFfi (x, modes, t) =>
+                let
+                    val () = if Settings.getLessSafeFfi () then
+                                 ()
+                             else
+                                 ErrorMsg.errorAt loc "To enable 'ffi' declarations, the .urp directive 'lessSafeFfi' is mandatory."
+
+                    val (t', _, gs1) = elabCon (env, denv) t
+                    val t' = normClassConstraint env t'
+                    val (env', n) = E.pushENamed env x t'
+                in
+                    ([(L'.DFfi (x, n, modes, t'), loc)], (env', denv, enD gs1 @ gs))
+                end
+
         (*val tcs = List.filter (fn TypeClass _ => true | _ => false) (#3 (#2 r))*)
     in
         (*prefaces "/elabDecl" [("d", SourcePrint.p_decl dAll),
diff --git a/src/elisp/urweb-mode.el b/src/elisp/urweb-mode.el
index f183a9ab..edbff1b0 100644
--- a/src/elisp/urweb-mode.el
+++ b/src/elisp/urweb-mode.el
@@ -139,7 +139,7 @@ See doc for the variable `urweb-mode-info'."
 	       "of" "open" "let" "in"
 	       "rec" "sequence" "sig" "signature" "cookie" "style" "task" "policy"
 	       "struct" "structure" "table" "view" "then" "type" "val" "where"
-	       "with"
+	       "with" "ffi"
 
                "Name" "Type" "Unit")
   "A regexp that matches any non-SQL keywords of Ur/Web.")
diff --git a/src/expl.sml b/src/expl.sml
index 0d4e63cc..3d784e3f 100644
--- a/src/expl.sml
+++ b/src/expl.sml
@@ -150,6 +150,7 @@ datatype decl' =
        | DTask of exp * exp
        | DPolicy of exp
        | DOnError of int * string list * string
+       | DFfi of string * int * Source.ffi_mode list * con
 
      and str' =
          StrConst of decl list
diff --git a/src/expl_env.sml b/src/expl_env.sml
index f5a5eb0a..5712a72d 100644
--- a/src/expl_env.sml
+++ b/src/expl_env.sml
@@ -346,6 +346,7 @@ fun declBinds env (d, loc) =
       | DTask _ => env
       | DPolicy _ => env
       | DOnError _ => env
+      | DFfi (x, n, _, t) => pushENamed env x n t
 
 fun sgiBinds env (sgi, loc) =
     case sgi of
diff --git a/src/expl_print.sml b/src/expl_print.sml
index a830dccb..22d246e2 100644
--- a/src/expl_print.sml
+++ b/src/expl_print.sml
@@ -731,6 +731,7 @@ fun p_decl env (dAll as (d, _) : decl) =
                            space,
                            p_exp env e1]
       | DOnError _ => string "ONERROR"
+      | DFfi _ => string "FFI"
 
 and p_str env (str, _) =
     case str of
diff --git a/src/expl_rename.sml b/src/expl_rename.sml
index 7e7a155a..bb763a60 100644
--- a/src/expl_rename.sml
+++ b/src/expl_rename.sml
@@ -219,6 +219,7 @@ fun renameDecl st (all as (d, loc)) =
         (case St.lookup (st, n) of
              NONE => all
            | SOME n' => (DOnError (n', xs, x), loc))
+      | DFfi (x, n, modes, t) => (DFfi (x, n, modes, renameCon st t), loc)
 
 and renameStr st (all as (str, loc)) =
     case str of
@@ -413,6 +414,15 @@ fun dupDecl (all as (d, loc), st) =
         (case St.lookup (st, n) of
              NONE => ([all], st)
            | SOME n' => ([(DOnError (n', xs, x), loc)], st))
+      | DFfi (x, n, modes, t) =>
+        let
+            val (st, n') = St.bind (st, n)
+            val t' = renameCon st t
+        in
+            ([(DFfi (x, n, modes, t'), loc),
+              (DVal (x, n', t', (ENamed n, loc)), loc)],
+             st)
+        end
 
 fun rename {NextId, FormalName, FormalId, Body = all as (str, loc)} =
     case str of
diff --git a/src/explify.sml b/src/explify.sml
index 4c60bd20..fd0f3277 100644
--- a/src/explify.sml
+++ b/src/explify.sml
@@ -198,6 +198,7 @@ fun explifyDecl (d, loc : EM.span) =
       | L.DTask (e1, e2) => SOME (L'.DTask (explifyExp e1, explifyExp e2), loc)
       | L.DPolicy e1 => SOME (L'.DPolicy (explifyExp e1), loc)
       | L.DOnError v => SOME (L'.DOnError v, loc)
+      | L.DFfi (x, n, modes, t) => SOME (L'.DFfi (x, n, modes, explifyCon t), loc)
 
 and explifyStr (str, loc) =
     case str of
diff --git a/src/jscomp.sig b/src/jscomp.sig
index 929c507d..5b8723b4 100644
--- a/src/jscomp.sig
+++ b/src/jscomp.sig
@@ -29,4 +29,8 @@ signature JSCOMP = sig
 
     val process : Mono.file -> Mono.file
 
+    val explainEmbed : bool ref
+    (* Output verbose error messages about inability to embed server-side
+     * values in client-side code? *)
+
 end
diff --git a/src/jscomp.sml b/src/jscomp.sml
index 4a2c0365..bcabed0b 100644
--- a/src/jscomp.sml
+++ b/src/jscomp.sml
@@ -41,6 +41,8 @@ structure TM = BinaryMapFn(struct
                            val compare = U.Typ.compare
                            end)
 
+val explainEmbed = ref false
+
 type state = {
      decls : (string * int * (string * int * typ option) list) list,
      script : string list,
@@ -267,7 +269,12 @@ fun process (file : file) =
                          ((EApp ((ENamed n', loc), e), loc), st)
                      end)
 
-              | _ => ((*Print.prefaces "Can't embed" [("t", MonoPrint.p_typ MonoEnv.empty t)];*)
+              | _ => (if !explainEmbed then
+                          Print.prefaces "Can't embed" [("loc", Print.PD.string (ErrorMsg.spanToString loc)),
+                                                        ("e", MonoPrint.p_exp MonoEnv.empty e),
+                                                        ("t", MonoPrint.p_typ MonoEnv.empty t)]
+                      else
+                          ();
                       raise CantEmbed t)
 
         fun unurlifyExp loc (t : typ, st) =
@@ -400,6 +407,9 @@ fun process (file : file) =
 
                 fun jsE inner (e as (_, loc), st) =
                     let
+                        (*val () = Print.prefaces "jsExp" [("e", MonoPrint.p_exp MonoEnv.empty e),
+                                                         ("loc", Print.PD.string (ErrorMsg.spanToString loc))]*)
+
                         val str = str loc
 
                         fun patCon pc =
diff --git a/src/main.mlton.sml b/src/main.mlton.sml
index 71fefc48..bfc18e59 100644
--- a/src/main.mlton.sml
+++ b/src/main.mlton.sml
@@ -174,6 +174,9 @@ fun oneRun args =
                      else
                          Settings.addLimit (class, n);
                  doArgs rest)
+              | "-explainEmbed" :: rest =>
+                (JsComp.explainEmbed := true;
+                 doArgs rest)
               | arg :: rest =>
                 (if size arg > 0 andalso String.sub (arg, 0) = #"-" then
                      raise Fail ("Unknown flag " ^ arg)
diff --git a/src/mono_opt.sml b/src/mono_opt.sml
index 228c53e6..ae306e68 100644
--- a/src/mono_opt.sml
+++ b/src/mono_opt.sml
@@ -118,6 +118,9 @@ fun unAs s =
     end
 
 fun checkUrl s = CharVector.all Char.isGraph s andalso Settings.checkUrl s
+val checkData = CharVector.all (fn ch => Char.isAlphaNum ch
+                                         orelse ch = #"_"
+                                         orelse ch = #"-")
 val checkAtom = CharVector.all (fn ch => Char.isAlphaNum ch
                                          orelse ch = #"+"
                                          orelse ch = #"-"
@@ -442,6 +445,13 @@ fun exp e =
       | ESignalBind ((ESignalReturn e1, loc), e2) =>
         optExp (EApp (e2, e1), loc)
 
+      | EFfiApp ("Basis", "blessData", [((se as EPrim (Prim.String s), loc), _)]) =>
+        (if checkData s then
+             ()
+         else
+             ErrorMsg.errorAt loc ("Invalid HTML5 data-* attribute " ^ s);
+         se)
+
       | EFfiApp ("Basis", "bless", [((se as EPrim (Prim.String s), loc), _)]) =>
         (if checkUrl s then
              ()
diff --git a/src/monoize.sml b/src/monoize.sml
index 000ba7b6..f7344fed 100644
--- a/src/monoize.sml
+++ b/src/monoize.sml
@@ -1,4 +1,4 @@
-(* Copyright (c) 2008-2013, Adam Chlipala
+(* Copyright (c) 2008-2014, Adam Chlipala
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -235,6 +235,7 @@ fun monoType env =
                   | L.CFfi ("Basis", "requestHeader") => (L'.TFfi ("Basis", "string"), loc)
                   | L.CFfi ("Basis", "responseHeader") => (L'.TFfi ("Basis", "string"), loc)
                   | L.CFfi ("Basis", "envVar") => (L'.TFfi ("Basis", "string"), loc)
+                  | L.CFfi ("Basis", "data_attr") => (L'.TFfi ("Basis", "string"), loc)
 
                   | L.CApp ((L.CFfi ("Basis", "serialized"), _), _) =>
                     (L'.TFfi ("Basis", "string"), loc)
@@ -2131,7 +2132,7 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                                                                     strcatComma
                                                                         (map (fn (x', _) =>
                                                                                  sc ("T_" ^ x
-										     ^ ""
+										     ^ "."
 										     ^ Settings.mangleSql x'))
                                                                              xts)) grouped)
                                                ],
@@ -3117,6 +3118,29 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                  fm)
             end
 
+          | L.EFfiApp ("Basis", "data_attr", [(s1, _), (s2, _)]) =>
+            let
+                val (s1, fm) = monoExp (env, st, fm) s1
+                val (s2, fm) = monoExp (env, st, fm) s2
+            in
+                ((L'.EStrcat ((L'.EPrim (Prim.String "data-"), loc),
+                              (L'.EStrcat ((L'.EFfiApp ("Basis", "blessData", [(s1, (L'.TFfi ("Basis", "string"), loc))]), loc),
+                                           (L'.EStrcat ((L'.EPrim (Prim.String "=\""), loc),
+                                                        (L'.EStrcat ((L'.EFfiApp ("Basis", "attrifyString", [(s2, (L'.TFfi ("Basis", "string"), loc))]), loc),
+                                                                     (L'.EPrim (Prim.String "\""), loc)), loc)),
+                                            loc)), loc)), loc),
+                 fm)
+            end
+
+          | L.EFfiApp ("Basis", "data_attrs", [(s1, _), (s2, _)]) =>
+            let
+                val (s1, fm) = monoExp (env, st, fm) s1
+                val (s2, fm) = monoExp (env, st, fm) s2
+            in
+                ((L'.EStrcat (s1, (L'.EStrcat ((L'.EPrim (Prim.String " "), loc), s2), loc)), loc),
+                 fm)
+            end
+
           | L.EFfiApp ("Basis", "css_url", [(s, _)]) =>
             let
                 val (s, fm) = monoExp (env, st, fm) s
@@ -3206,7 +3230,7 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                         (L.ECApp (
                          (L.ECApp (
 			  (L.EFfi ("Basis", "tag"),
-                           _), (L.CRecord (_, attrsGiven), _)), _), _), _), _), _), _), _), _), _), _), _), _), _), _), _),
+                           _), (L.CRecord (_, attrsGiven), _)), _), _), _), ctxOuter), _), _), _), _), _), _), _), _), _), _), _),
 		  class), _),
 	         dynClass), _),
                 style), _),
@@ -3317,6 +3341,12 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
 
                         val (s, fm) = foldl (fn (("Action", _, _), acc) => acc
                                               | (("Source", _, _), acc) => acc
+                                              | (("Data", e, _), (s, fm)) =>
+                                                ((L'.EStrcat (s,
+                                                              (L'.EStrcat (
+                                                               (L'.EPrim (Prim.String " "), loc),
+                                                               e), loc)), loc),
+                                                 fm)
                                               | ((x, e, t), (s, fm)) =>
                                                 case t of
                                                     (L'.TFfi ("Basis", "bool"), _) =>
@@ -3551,6 +3581,19 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                                                       (L'.EPrim (Prim.String ")"), loc)), loc)), loc)
                         end
 
+                fun inTag tag' = case ctxOuter of
+				     (L.CRecord (_, ctx), _) =>
+				     List.exists (fn ((L.CName tag'', _), _) => tag'' = tag'
+                                                   | _ => false) ctx
+                                  | _ => false
+
+                fun pnode () = if inTag "Tr" then
+			           "tr"
+                               else if inTag "Table" then
+			           "table"
+                               else
+			           "span"
+
 		val baseAll as (base, fm) =
                     case tag of
 			"body" => let
@@ -3573,24 +3616,12 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
 
                       | "dyn" =>
 			let
-                            fun inTag tag = case targs of
-						(L.CRecord (_, ctx), _) :: _ =>
-						List.exists (fn ((L.CName tag', _), _) => tag' = tag
-                                                              | _ => false) ctx
-                                              | _ => false
-
-                            val tag = if inTag "Tr" then
-					  "tr"
-                                      else if inTag "Table" then
-					  "table"
-                                      else
-					  "span"
 			in
                             case attrs of
 				[("Signal", e, _)] =>
 				((L'.EStrcat
                                       ((L'.EPrim (Prim.String ("<script type=\"text/javascript\">dyn(\""
-                                                               ^ tag ^ "\", execD(")), loc),
+                                                               ^ pnode () ^ "\", execD(")), loc),
                                        (L'.EStrcat ((L'.EJavaScript (L'.Script, e), loc),
                                                     (L'.EPrim (Prim.String ("))</script>")), loc)), loc)), loc),
 				 fm)
@@ -3804,7 +3835,9 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
 		    L'.ENone _ =>
 		    (case #1 dynStyle of
 		         L'.ENone _ => baseAll
-		       | L'.ESome (_, ds) => (strcat [str "<script type=\"text/javascript\">dynClass(execD(",
+		       | L'.ESome (_, ds) => (strcat [str "<script type=\"text/javascript\">dynClass(\"",
+                                                      str (pnode ()),
+                                                      str "\",execD(",
 				                      (L'.EJavaScript (L'.Script, base), loc),
 				                      str "),null,execD(",
 				                      (L'.EJavaScript (L'.Script, ds), loc),
@@ -3822,7 +3855,9 @@ fun monoExp (env, st, fm) (all as (e, loc)) =
                                   | _ => (E.errorAt loc "Absence/presence of 'dynStyle' unknown";
                                           str "null")
                     in
-                        (strcat [str "<script type=\"text/javascript\">dynClass(execD(",
+                        (strcat [str "<script type=\"text/javascript\">dynClass(\"",
+                                 str (pnode ()),
+                                 str "\",execD(",
 				 (L'.EJavaScript (L'.Script, base), loc),
 				 str "),execD(",
 				 (L'.EJavaScript (L'.Script, dc), loc),
diff --git a/src/settings.sig b/src/settings.sig
index 20dd00c2..29c4c506 100644
--- a/src/settings.sig
+++ b/src/settings.sig
@@ -78,18 +78,22 @@ signature SETTINGS = sig
 
     (* Which FFI functions should not have their calls removed or reordered, but cause no lasting effects? *)
     val setBenignEffectful : ffi list -> unit
+    val addBenignEffectful : ffi -> unit
     val isBenignEffectful : ffi -> bool
 
     (* Which FFI functions may only be run in clients? *)
     val setClientOnly : ffi list -> unit
+    val addClientOnly : ffi -> unit
     val isClientOnly : ffi -> bool
 
     (* Which FFI functions may only be run on servers? *)
     val setServerOnly : ffi list -> unit
+    val addServerOnly : ffi -> unit
     val isServerOnly : ffi -> bool
 
     (* Which FFI functions may be run in JavaScript?  (JavaScript function names included) *)
     val setJsFuncs : (ffi * string) list -> unit
+    val addJsFunc : ffi * string -> unit
     val jsFunc : ffi -> string option
     val allJsFuncs : unit -> (ffi * string) list
 
@@ -271,4 +275,7 @@ signature SETTINGS = sig
 
     val setIsHtml5 : bool -> unit
     val getIsHtml5 : unit -> bool
+
+    val setLessSafeFfi : bool -> unit
+    val getLessSafeFfi : unit -> bool
 end
diff --git a/src/settings.sml b/src/settings.sml
index 6282577d..f00a4853 100644
--- a/src/settings.sml
+++ b/src/settings.sml
@@ -194,6 +194,7 @@ val benignBase = basis ["get_cookie",
 
 val benign = ref benignBase
 fun setBenignEffectful ls = benign := S.addList (benignBase, ls)
+fun addBenignEffectful x = benign := S.add (!benign, x)
 fun isBenignEffectful x = S.member (!benign, x)
 
 val clientBase = basis ["get_client_source",
@@ -225,6 +226,7 @@ val clientBase = basis ["get_client_source",
                         "giveFocus"]
 val client = ref clientBase
 fun setClientOnly ls = client := S.addList (clientBase, ls)
+fun addClientOnly x = client := S.add (!client, x)
 fun isClientOnly x = S.member (!client, x)
 
 val serverBase = basis ["requestHeader",
@@ -240,6 +242,7 @@ val serverBase = basis ["requestHeader",
                         "firstFormField"]
 val server = ref serverBase
 fun setServerOnly ls = server := S.addList (serverBase, ls)
+fun addServerOnly x = server := S.add (!server, x)
 fun isServerOnly x = S.member (!server, x)
 
 val basisM = foldl (fn ((k, v : string), m) => M.insert (m, ("Basis", k), v)) M.empty
@@ -309,6 +312,7 @@ val jsFuncsBase = basisM [("alert", "alert"),
 
                           ("checkUrl", "checkUrl"),
                           ("bless", "bless"),
+                          ("blessData", "blessData"),
 
                           ("eq_time", "eq"),
                           ("lt_time", "lt"),
@@ -363,6 +367,7 @@ val jsFuncsBase = basisM [("alert", "alert"),
 val jsFuncs = ref jsFuncsBase
 fun setJsFuncs ls = jsFuncs := foldl (fn ((k, v), m) => M.insert (m, k, v)) jsFuncsBase ls
 fun jsFunc x = M.find (!jsFuncs, x)
+fun addJsFunc (k, v) = jsFuncs := M.insert (!jsFuncs, k, v)
 fun allJsFuncs () = M.listItemsi (!jsFuncs)
 
 datatype pattern_kind = Exact | Prefix
@@ -734,4 +739,8 @@ val html5 = ref false
 fun setIsHtml5 b = html5 := b
 fun getIsHtml5 () = !html5
 
+val less = ref false
+fun setLessSafeFfi b = less := b
+fun getLessSafeFfi () = !less
+
 end
diff --git a/src/source.sml b/src/source.sml
index 639ea716..2a741dd9 100644
--- a/src/source.sml
+++ b/src/source.sml
@@ -125,7 +125,7 @@ and exp' =
 
   | EKAbs of string * exp
 
-  | ERecord of (con * exp) list
+  | ERecord of (con * exp) list * bool
   | EField of exp * con
   | EConcat of exp * exp
   | ECut of exp * con
@@ -147,6 +147,13 @@ and pat = pat' located
 and exp = exp' located
 and edecl = edecl' located
 
+datatype ffi_mode =
+         Effectful
+       | BenignEffectful
+       | ClientOnly
+       | ServerOnly
+       | JsFunc of string
+
 datatype decl' =
          DCon of string * kind option * con
        | DDatatype of (string * string list * (string * con option) list) list
@@ -169,6 +176,7 @@ datatype decl' =
        | DTask of exp * exp
        | DPolicy of exp
        | DOnError of string * string list * string
+       | DFfi of string * ffi_mode list * con
 
      and str' =
          StrConst of decl list
diff --git a/src/source_print.sml b/src/source_print.sml
index ce095542..db56a0db 100644
--- a/src/source_print.sml
+++ b/src/source_print.sml
@@ -277,14 +277,20 @@ fun p_exp' par (e, _) =
                                             space,
                                             string "!"])
 
-      | ERecord xes => box [string "{",
-                            p_list (fn (x, e) =>
-                                       box [p_name x,
-                                            space,
-                                            string "=",
-                                            space,
-                                            p_exp e]) xes,
-                            string "}"]
+      | ERecord (xes, flex) => box [string "{",
+                                    p_list (fn (x, e) =>
+                                               box [p_name x,
+                                                    space,
+                                                    string "=",
+                                                    space,
+                                                    p_exp e]) xes,
+                                    if flex then
+                                        box [string ",",
+                                             space,
+                                             string "..."]
+                                    else
+                                        box [],
+                                    string "}"]
       | EField (e, c) => box [p_exp' true e,
                               string ".",
                               p_con' true c]
@@ -668,6 +674,7 @@ fun p_decl ((d, _) : decl) =
                            space,
                            p_exp e1]
       | DOnError _ => string "ONERROR"
+      | DFfi _ => string "FFI"
 
 and p_str (str, _) =
     case str of
diff --git a/src/unnest.sml b/src/unnest.sml
index 17bfd39f..fceb5026 100644
--- a/src/unnest.sml
+++ b/src/unnest.sml
@@ -452,6 +452,7 @@ fun unnest file =
                   | DTask _ => explore ()
                   | DPolicy _ => explore ()
                   | DOnError _ => default ()
+                  | DFfi _ => default ()
             end
 
         and doStr (all as (str, loc), st) =
diff --git a/src/urweb.grm b/src/urweb.grm
index 7063af38..157ecfac 100644
--- a/src/urweb.grm
+++ b/src/urweb.grm
@@ -1,4 +1,4 @@
-(* Copyright (c) 2008-2012, Adam Chlipala
+(* Copyright (c) 2008-2014, Adam Chlipala
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -225,7 +225,7 @@ fun tagIn bt =
 
 datatype prop_kind = Delete | Update
 
-datatype attr = Class of exp | DynClass of exp | Style of exp | DynStyle of exp | Normal of con * exp
+datatype attr = Class of exp | DynClass of exp | Style of exp | DynStyle of exp | Normal of con * exp | Data of string * exp
 
 fun patType loc (p : pat) =
     case #1 p of
@@ -322,6 +322,39 @@ fun applyWindow loc e window =
         (EApp (e', ob), loc)
     end
 
+fun patternOut (e : exp) =
+    case #1 e of
+        EWild => (PWild, #2 e)
+      | EVar ([], x, Infer) =>
+        if Char.isUpper (String.sub (x, 0)) then
+            (PCon ([], x, NONE), #2 e)
+        else
+            (PVar x, #2 e)
+      | EVar (xs, x, Infer) =>
+        if Char.isUpper (String.sub (x, 0)) then
+            (PCon (xs, x, NONE), #2 e)
+        else
+            (ErrorMsg.errorAt (#2 e) "Badly capitalized constructor name in pattern";
+             (PWild, #2 e))
+      | EPrim p => (PPrim p, #2 e)
+      | EApp ((EVar (xs, x, Infer), _), e') =>
+        (PCon (xs, x, SOME (patternOut e')), #2 e)
+      | ERecord (xes, flex) =>
+        (PRecord (map (fn (x, e') =>
+                          let
+                              val x =
+                                  case #1 x of
+                                      CName x => x
+                                    | _ => (ErrorMsg.errorAt (#2 e) "Field name not constant in pattern";
+                                            "")
+                          in
+                              (x, patternOut e')
+                          end) xes, flex), #2 e)
+      | EAnnot (e', t) =>
+        (PAnnot (patternOut e', t), #2 e)
+      | _ => (ErrorMsg.errorAt (#2 e) "This is an expression but not a pattern.";
+              (PWild, #2 e))
+
 %%
 %header (functor UrwebLrValsFn(structure Token : TOKEN))
 
@@ -332,7 +365,7 @@ fun applyWindow loc e window =
  | LPAREN | RPAREN | LBRACK | RBRACK | LBRACE | RBRACE
  | EQ | COMMA | COLON | DCOLON | DCOLONWILD | TCOLON | TCOLONWILD | DOT | HASH | UNDER | UNDERUNDER | BAR
  | PLUS | MINUS | DIVIDE | DOTDOTDOT | MOD | AT
- | CON | LTYPE | VAL | REC | AND | FUN | MAP | UNIT | KUNIT | CLASS
+ | CON | LTYPE | VAL | REC | AND | FUN | MAP | UNIT | KUNIT | CLASS | FFI
  | DATATYPE | OF
  | TYPE | NAME
  | ARROW | LARROW | DARROW | STAR | SEMI | KARROW | DKARROW | BANG
@@ -428,13 +461,13 @@ fun applyWindow loc e window =
  | eapps of exp
  | eterm of exp
  | etuple of exp list
- | rexp of (con * exp) list
+ | rexp of (con * exp) list * bool
  | xml of exp
  | xmlOne of exp
  | xmlOpt of exp
  | tag of (string * exp) * exp option * exp option * exp
  | tagHead of string * exp
- | bind of string * con option * exp
+ | bind of pat * con option * exp
  | edecl of edecl
  | edecls of edecl list
 
@@ -453,7 +486,7 @@ fun applyWindow loc e window =
  | rpat of (string * pat) list * bool
  | ptuple of pat list
 
- | attrs of exp option * exp option * exp option * exp option * (con * exp) list
+ | attrs of exp option * exp option * exp option * exp option * (string * exp) list * (con * exp) list
  | attr of attr
  | attrv of exp
 
@@ -499,6 +532,9 @@ fun applyWindow loc e window =
  | enterDml of unit
  | leaveDml of unit
 
+ | ffi_mode of ffi_mode
+ | ffi_modes of ffi_mode list
+
 
 %verbose                                (* print summary of errors *)
 %pos int                                (* positions *)
@@ -612,6 +648,7 @@ decl   : CON SYMBOL cargl2 kopt EQ cexp (let
        | STYLE SYMBOL                   ([(DStyle SYMBOL, s (STYLEleft, SYMBOLright))])
        | TASK eapps EQ eexp             ([(DTask (eapps, eexp), s (TASKleft, eexpright))])
        | POLICY eexp                    ([(DPolicy eexp, s (POLICYleft, eexpright))])
+       | FFI SYMBOL ffi_modes COLON cexp([(DFfi (SYMBOL, ffi_modes, cexp), s (FFIleft, cexpright))])
 
 dtype  : SYMBOL dargs EQ barOpt dcons   (SYMBOL, dargs, dcons)
 
@@ -730,10 +767,10 @@ cst    : UNIQUE tnames                  (let
                                              val e = (EApp (e, mat), loc)
                                              val e = (EApp (e, texp), loc)
                                          in
-                                             (EApp (e, (ERecord [((CName "OnDelete", loc),
-                                                                  findMode Delete),
-                                                                 ((CName "OnUpdate", loc),
-                                                                  findMode Update)], loc)), loc)
+                                             (EApp (e, (ERecord ([((CName "OnDelete", loc),
+                                                                   findMode Delete),
+                                                                  ((CName "OnUpdate", loc),
+                                                                   findMode Update)], false), loc)), loc)
                                          end)
 
        | LBRACE eexp RBRACE             (eexp)
@@ -779,7 +816,7 @@ pk     : LBRACE LBRACE eexp RBRACE RBRACE (eexp)
                                              val witness = map (fn (c, _) =>
                                                                    (c, (EWild, loc)))
                                                            (#1 tnames :: #2 tnames)
-                                             val witness = (ERecord witness, loc)
+                                             val witness = (ERecord (witness, false), loc)
                                          in
                                              (EApp (e, witness), loc)
                                          end)
@@ -1136,11 +1173,17 @@ eexp   : eapps                          (case #1 eapps of
                                          end)
        | bind SEMI eexp                 (let
                                              val loc = s (bindleft, eexpright)
-                                             val (v, to, e1) = bind
+                                             val (p, to, e1) = bind
                                              val e = (EVar (["Basis"], "bind", Infer), loc)
                                              val e = (EApp (e, e1), loc)
+
+                                             val f = case #1 p of
+                                                         PVar v => (EAbs (v, to, eexp), loc)
+                                                       | _ => (EAbs ("$x", to,
+                                                                     (ECase ((EVar ([], "$x", Infer), loc),
+                                                                             [(p, eexp)]), loc)), loc)
                                          in
-                                             (EApp (e, (EAbs (v, to, eexp), loc)), loc)
+                                             (EApp (e, f), loc)
                                          end)
        | eexp EQ eexp                   (native_op ("eq", eexp1, eexp2, s (eexp1left, eexp2right)))
        | eexp NE eexp                   (native_op ("ne", eexp1, eexp2, s (eexp1left, eexp2right)))
@@ -1181,17 +1224,17 @@ eexp   : eapps                          (case #1 eapps of
                                              val loc = s (eappsleft, eexpright)
                                          in
                                              (EApp ((EVar (["Basis"], "Cons", Infer), loc),
-                                                    (ERecord [((CName "1", loc),
-                                                               eapps),
-                                                              ((CName "2", loc),
-                                                               eexp)], loc)), loc)
+                                                    (ERecord ([((CName "1", loc),
+                                                                eapps),
+                                                               ((CName "2", loc),
+                                                                eexp)], false), loc)), loc)
                                          end)
 
-bind   : SYMBOL LARROW eapps            (SYMBOL, NONE, eapps)
+bind   : eapps LARROW eapps             (patternOut eapps1, NONE, eapps2)
        | eapps                          (let
                                              val loc = s (eappsleft, eappsright)
                                          in
-                                             ("_", SOME (TRecord (CRecord [], loc), loc), eapps)
+                                             ((PVar "_", loc), SOME (TRecord (CRecord [], loc), loc), eapps)
                                          end)
 
 eargs  : earg                           (earg)
@@ -1289,7 +1332,7 @@ eterm  : LPAREN eexp RPAREN             (#1 eexp, s (LPARENleft, RPARENright))
                                          in
                                              (ERecord (ListUtil.mapi (fn (i, e) =>
                                                                          ((CName (Int.toString (i + 1)), loc),
-                                                                          e)) etuple), loc)
+                                                                          e)) etuple, false), loc)
                                          end)
 
        | path                           (EVar (#1 path, #2 path, Infer), s (pathleft, pathright))
@@ -1299,7 +1342,8 @@ eterm  : LPAREN eexp RPAREN             (#1 eexp, s (LPARENleft, RPARENright))
        | AT cpath                       (EVar (#1 cpath, #2 cpath, TypesOnly), s (ATleft, cpathright))
        | AT AT cpath                    (EVar (#1 cpath, #2 cpath, DontInfer), s (AT1left, cpathright))
        | LBRACE rexp RBRACE             (ERecord rexp, s (LBRACEleft, RBRACEright))
-       | UNIT                           (ERecord [], s (UNITleft, UNITright))
+       | LBRACE RBRACE                  (ERecord ([], false), s (LBRACEleft, RBRACEright))
+       | UNIT                           (ERecord ([], false), s (UNITleft, UNITright))
 
        | INT                            (EPrim (Prim.Int INT), s (INTleft, INTright))
        | FLOAT                          (EPrim (Prim.Float FLOAT), s (FLOATleft, FLOATright))
@@ -1386,7 +1430,7 @@ eterm  : LPAREN eexp RPAREN             (#1 eexp, s (LPARENleft, RPARENright))
                                                                        ^ " vs. " ^ Int.toString (length sqlexps) ^ ")")
                                              else
                                                  ();
-                                             (EApp (e, (ERecord (ListPair.zip (fields, sqlexps)), loc)), loc)
+                                             (EApp (e, (ERecord (ListPair.zip (fields, sqlexps), false), loc)), loc)
                                          end)
        | LPAREN enterDml UPDATE texp SET fsets CWHERE sqlexp leaveDml RPAREN
                                         (let
@@ -1394,7 +1438,7 @@ eterm  : LPAREN eexp RPAREN             (#1 eexp, s (LPARENleft, RPARENright))
 
                                              val e = (EVar (["Basis"], "update", Infer), loc)
                                              val e = (ECApp (e, (CWild (KRecord (KType, loc), loc), loc)), loc)
-                                             val e = (EApp (e, (ERecord fsets, loc)), loc)
+                                             val e = (EApp (e, (ERecord (fsets, false), loc)), loc)
                                              val e = (EApp (e, texp), loc)
                                          in
                                              (EApp (e, sqlexp), loc)
@@ -1486,9 +1530,9 @@ rpat   : CSYMBOL EQ pat                 ([(CSYMBOL, pat)], false)
 ptuple : pat COMMA pat                  ([pat1, pat2])
        | pat COMMA ptuple               (pat :: ptuple)
 
-rexp   :                                ([])
-       | ident EQ eexp                  ([(ident, eexp)])
-       | ident EQ eexp COMMA rexp       ((ident, eexp) :: rexp)
+rexp   : DOTDOTDOT                      ([], true)
+       | ident EQ eexp                  ([(ident, eexp)], false)
+       | ident EQ eexp COMMA rexp       ((ident, eexp) :: #1 rexp, #2 rexp)
 
 xml    : xmlOne xml                     (let
                                              val pos = s (xmlOneleft, xmlright)
@@ -1602,9 +1646,33 @@ tag    : tagHead attrs                  (let
                                                         | SOME e => (EApp ((EVar (["Basis"], "Some", Infer), pos),
                                                                            e), pos)
                                              val e = (EApp (e, eo), pos)
-                                             val e = (EApp (e, (ERecord (#5 attrs), pos)), pos)
+
+                                             val atts = case #5 attrs of
+                                                            [] => #6 attrs
+                                                          | data :: datas =>
+                                                            let
+                                                                fun doOne (name, value) =
+                                                                    let
+                                                                        val e = (EVar (["Basis"], "data_attr", Infer), pos)
+                                                                        val e = (EApp (e, (EPrim (Prim.String name), pos)), pos)
+                                                                    in
+                                                                        (EApp (e, value), pos)
+                                                                    end
+
+                                                                val datas' = foldl (fn (nv, acc) =>
+                                                                                       let
+                                                                                           val e = (EVar (["Basis"], "data_attrs", Infer), pos)
+                                                                                           val e = (EApp (e, acc), pos)
+                                                                                       in
+                                                                                           (EApp (e, doOne nv), pos)
+                                                                                       end) (doOne data) datas
+                                                            in
+                                                                ((CName "Data", pos), datas') :: #6 attrs
+                                                            end
+
+                                             val e = (EApp (e, (ERecord (atts, false), pos)), pos)
                                              val e = (EApp (e, (EApp (#2 tagHead,
-                                                                      (ERecord [], pos)), pos)), pos)
+                                                                      (ERecord ([], false), pos)), pos)), pos)
                                          in
                                              (tagHead, #1 attrs, #2 attrs, e)
                                          end)
@@ -1618,7 +1686,7 @@ tagHead: BEGIN_TAG                      (let
                                          end)
        | tagHead LBRACE cexp RBRACE     (#1 tagHead, (ECApp (#2 tagHead, cexp), s (tagHeadleft, RBRACEright)))
                                           
-attrs  :                                (NONE, NONE, NONE, NONE, [])
+attrs  :                                (NONE, NONE, NONE, NONE, [], [])
        | attr attrs                     (let
                                              val loc = s (attrleft, attrsright)
                                          in
@@ -1627,24 +1695,26 @@ attrs  :                                (NONE, NONE, NONE, NONE, [])
                                                  (case #1 attrs of
                                                       NONE => ()
                                                     | SOME _ => ErrorMsg.errorAt loc "Multiple classes specified for tag";
-                                                  (SOME e, #2 attrs, #3 attrs, #4 attrs, #5 attrs))
+                                                  (SOME e, #2 attrs, #3 attrs, #4 attrs, #5 attrs, #6 attrs))
                                                | DynClass e =>
                                                  (case #2 attrs of
                                                       NONE => ()
                                                     | SOME _ => ErrorMsg.errorAt loc "Multiple dynamic classes specified for tag";
-                                                  (#1 attrs, SOME e, #3 attrs, #4 attrs, #5 attrs))
+                                                  (#1 attrs, SOME e, #3 attrs, #4 attrs, #5 attrs, #6 attrs))
                                                | Style e =>
                                                  (case #3 attrs of
                                                       NONE => ()
                                                     | SOME _ => ErrorMsg.errorAt loc "Multiple styles specified for tag";
-                                                  (#1 attrs, #2 attrs, SOME e, #4 attrs, #5 attrs))
+                                                  (#1 attrs, #2 attrs, SOME e, #4 attrs, #5 attrs, #6 attrs))
                                                | DynStyle e =>
                                                  (case #4 attrs of
                                                       NONE => ()
                                                     | SOME _ => ErrorMsg.errorAt loc "Multiple dynamic classes specified for tag";
-                                                  (#1 attrs, #2 attrs, #3 attrs, SOME e, #5 attrs))
+                                                  (#1 attrs, #2 attrs, #3 attrs, SOME e, #5 attrs, #6 attrs))
+                                               | Data xe =>
+                                                 (#1 attrs, #2 attrs, #3 attrs, #4 attrs, xe :: #5 attrs, #6 attrs)
                                                | Normal xe =>
-                                                 (#1 attrs, #2 attrs, #3 attrs, #4 attrs, xe :: #5 attrs)
+                                                 (#1 attrs, #2 attrs, #3 attrs, #4 attrs, #5 attrs, xe :: #6 attrs)
                                          end)
 
 attr   : SYMBOL EQ attrv                (case SYMBOL of
@@ -1653,23 +1723,26 @@ attr   : SYMBOL EQ attrv                (case SYMBOL of
                                            | "style" => Style attrv
 					   | "dynStyle" => DynStyle attrv
 					   | _ =>
-                                             let
-                                                 val sym = makeAttr SYMBOL
-                                             in
-                                                 Normal ((CName sym, s (SYMBOLleft, SYMBOLright)),
-                                                         if (sym = "Href" orelse sym = "Src")
-                                                            andalso (case #1 attrv of
-                                                                         EPrim _ => true
-                                                                       | _ => false) then
-                                                             let
-                                                                 val loc = s (attrvleft, attrvright)
-                                                             in
-                                                                 (EApp ((EVar (["Basis"], "bless", Infer), loc),
-                                                                        attrv), loc)
-                                                             end
-                                                         else
-                                                             attrv)
-                                             end)
+                                             if String.isPrefix "data-" SYMBOL then
+                                                 Data (String.extract (SYMBOL, 5, NONE), attrv)
+                                             else
+                                                 let
+                                                     val sym = makeAttr SYMBOL
+                                                 in
+                                                     Normal ((CName sym, s (SYMBOLleft, SYMBOLright)),
+                                                             if (sym = "Href" orelse sym = "Src")
+                                                                andalso (case #1 attrv of
+                                                                             EPrim _ => true
+                                                                           | _ => false) then
+                                                                 let
+                                                                     val loc = s (attrvleft, attrvright)
+                                                                 in
+                                                                     (EApp ((EVar (["Basis"], "bless", Infer), loc),
+                                                                            attrv), loc)
+                                                                 end
+                                                             else
+                                                                 attrv)
+                                                 end)
                 
 attrv  : INT                            (EPrim (Prim.Int INT), s (INTleft, INTright))
        | FLOAT                          (EPrim (Prim.Float FLOAT), s (FLOATleft, FLOATright))
@@ -1679,14 +1752,14 @@ attrv  : INT                            (EPrim (Prim.Int INT), s (INTleft, INTri
 query  : query1 obopt lopt ofopt        (let
                                              val loc = s (query1left, query1right)
 
-                                             val re = (ERecord [((CName "Rows", loc),
-                                                                 query1),
-                                                                ((CName "OrderBy", loc),
-                                                                 obopt),
-                                                                ((CName "Limit", loc),
-                                                                 lopt),
-                                                                ((CName "Offset", loc),
-                                                                 ofopt)], loc)
+                                             val re = (ERecord ([((CName "Rows", loc),
+                                                                  query1),
+                                                                 ((CName "OrderBy", loc),
+                                                                  obopt),
+                                                                 ((CName "Limit", loc),
+                                                                  lopt),
+                                                                 ((CName "Offset", loc),
+                                                                  ofopt)], false), loc)
                                          in
                                              (EApp ((EVar (["Basis"], "sql_query", Infer), loc), re), loc)
                                          end)
@@ -1767,21 +1840,21 @@ query1 : SELECT dopt select FROM tables wopt gopt hopt
                                              val e = (EVar (["Basis"], "sql_query1", Infer), loc)
                                              val e = (ECApp (e, (CRecord (map (fn nm => (nm, (CUnit, loc))) empties),
                                                                  loc)), loc)
-                                             val re = (ERecord [((CName "Distinct", loc),
-                                                                 dopt),
-                                                                ((CName "From", loc),
-                                                                 #2 tables),
-                                                                ((CName "Where", loc),
-                                                                 wopt),
-                                                                ((CName "GroupBy", loc),
-                                                                 grp),
-                                                                ((CName "Having", loc),
-                                                                 hopt),
-                                                                ((CName "SelectFields", loc),
-                                                                 (ECApp ((EVar (["Basis"], "sql_subset", Infer), loc),
-                                                                         sel), loc)),
-                                                                ((CName "SelectExps", loc),
-                                                                 (ERecord exps, loc))], loc)
+                                             val re = (ERecord ([((CName "Distinct", loc),
+                                                                  dopt),
+                                                                 ((CName "From", loc),
+                                                                  #2 tables),
+                                                                 ((CName "Where", loc),
+                                                                  wopt),
+                                                                 ((CName "GroupBy", loc),
+                                                                  grp),
+                                                                 ((CName "Having", loc),
+                                                                  hopt),
+                                                                 ((CName "SelectFields", loc),
+                                                                  (ECApp ((EVar (["Basis"], "sql_subset", Infer), loc),
+                                                                          sel), loc)),
+                                                                 ((CName "SelectExps", loc),
+                                                                  (ERecord (exps, false), loc))], false), loc)
 
                                              val e = (EApp (e, re), loc)
                                          in
@@ -1907,6 +1980,7 @@ fitem  : table'                         ([#1 table'], #2 table')
                                          in
                                              ([tname], (EApp (e, query), loc))
                                          end)
+       | LPAREN fitem RPAREN            (fitem)
 
 tname  : CSYMBOL                        (CName CSYMBOL, s (CSYMBOLleft, CSYMBOLright))
        | LBRACE cexp RBRACE             (cexp)
@@ -2197,3 +2271,16 @@ sqlagg : AVG                             ("avg")
        | SUM                             ("sum")
        | MIN                             ("min")
        | MAX                             ("max")
+
+ffi_mode : SYMBOL                        (case SYMBOL of
+                                              "effectful" => Effectful
+                                            | "benignEffectful" => BenignEffectful
+                                            | "clientOnly" => ClientOnly
+                                            | "serverOnly" => ServerOnly
+                                            | _ => (ErrorMsg.errorAt (s (SYMBOLleft, SYMBOLright)) "Invalid FFI mode"; Effectful))
+         | SYMBOL STRING                 (case SYMBOL of
+                                              "jsFunc" => JsFunc STRING
+                                            | _ => (ErrorMsg.errorAt (s (SYMBOLleft, SYMBOLright)) "Invalid FFI mode"; Effectful))
+
+ffi_modes :                              ([])
+          | ffi_mode ffi_modes           (ffi_mode :: ffi_modes)
diff --git a/src/urweb.lex b/src/urweb.lex
index 293c6dc6..15ae448e 100644
--- a/src/urweb.lex
+++ b/src/urweb.lex
@@ -445,6 +445,7 @@ xint = x[0-9a-fA-F][0-9a-fA-F];
 <INITIAL> "style"     => (Tokens.STYLE (pos yypos, pos yypos + size yytext));
 <INITIAL> "task"      => (Tokens.TASK (pos yypos, pos yypos + size yytext));
 <INITIAL> "policy"    => (Tokens.POLICY (pos yypos, pos yypos + size yytext));
+<INITIAL> "ffi"       => (Tokens.FFI (pos yypos, pos yypos + size yytext));
 
 <INITIAL> "Type"      => (Tokens.TYPE (pos yypos, pos yypos + size yytext));
 <INITIAL> "Name"      => (Tokens.NAME (pos yypos, pos yypos + size yytext));