first iteration of "typeOf" command

10 files changed, 1194 insertions, 0 deletions

diff --git a/src/compiler.sig b/src/compiler.sig
index 6ed2f9a6..7f724b0f 100644
--- a/src/compiler.sig
+++ b/src/compiler.sig
@@ -215,6 +215,7 @@ signature COMPILER = sig
     val addModuleRoot : string * string -> unit
 
     val moduleOf : string -> string
+    val typeOf : string -> Print.PD.pp_desc
 
     val setStop : string -> unit
     (* Stop compilation after this phase. *)
diff --git a/src/compiler.sml b/src/compiler.sml
index 0aba3a40..46a035ee 100644
--- a/src/compiler.sml
+++ b/src/compiler.sml
@@ -1781,4 +1781,191 @@ fun moduleOf fname =
             end
     end
 
+fun isPosIn row col span =
+    let
+        val start = #first span
+        val end_ = #last span
+    in
+        ((#line start < row) orelse
+         (#line start = row) andalso (#char start <= col))
+        andalso 
+        ((#line end_ > row) orelse
+         (#line end_ = row) andalso (#char end_ >= col))
+    end
+
+fun isSmallerThan (s1: ErrorMsg.span) (s2: ErrorMsg.span) =
+    (#line (#first s1) > #line (#first s2) orelse
+     (#line (#first s1) = #line (#first s2) andalso (#char (#first s1) >= #char (#first s2))))
+    andalso 
+    (#line (#last s1) < #line (#last s2) orelse
+     (#line (#last s1) = #line (#last s2) andalso (#char (#last s1) <= #char (#last s2)))) 
+
+datatype foundStuff =
+         Kind of Elab.kind
+       | Con of Elab.con
+       | Exp of Elab.exp
+       | Sgn_item of Elab.sgn_item
+       | Sgn of Elab.sgn
+       | Str of Elab.str
+       | Decl of Elab.decl
+
+fun getSpan (f: foundStuff * ElabEnv.env) =
+    case #1 f of
+        Kind k => #2 k
+      | Con c => #2 c
+      | Exp e => #2 e
+      | Sgn_item si => #2 si
+      | Sgn s => #2 s
+      | Str s => #2 s
+      | Decl d => #2 d
+
+fun getTypeAt file row col =
+    if not (!Elaborate.incremental)
+    then Print.PD.string "ERROR: urweb daemon is needed to use typeOf command"
+    else
+        case ModDb.lookupForTooling (moduleOf file) of
+            NONE => Print.PD.string ("ERROR: No module found: " ^ moduleOf file)
+          | SOME (decl, deps) => 
+            let
+                (* TODO Top is not always found as a dep *)
+                val () = ElabUtilPos.mliftConInCon := ElabEnv.mliftConInCon
+                (* Adding dependencies to environment *)
+                val env = List.foldl (fn (d, e) => ElabEnv.declBinds e d)
+                                     ElabEnv.empty
+                                     deps
+                (* Adding previous declarations to environment *)
+                val env =
+                    case #1 decl of 
+                        Elab.DStr (name, _, sgn, str) =>
+                        (case #1 str of
+                             Elab.StrConst decls =>
+                             List.foldl
+                                 (fn (d, e) => ElabEnv.declBinds e d)
+                                 env
+                                 decls
+                           | _ => env)
+                      | Elab.DFfiStr _ => env
+                      | _ => env
+                (* Look for item under cursor *)
+                val (atPosition, env) =
+                    ElabUtilPos.Decl.foldB
+                        { kind = fn (env, (k, span), acc) =>
+                                    if isPosIn row col span andalso isSmallerThan span (getSpan acc)
+                                    then (Kind (k, span), env)
+                                    else acc ,
+                          con = fn (env, (k, span), acc) =>
+                                   if isPosIn row col span andalso isSmallerThan span (getSpan acc)
+                                   then (Con (k, span), env)
+                                   else acc,
+                          exp = fn (env, (k, span), acc) =>
+                                   if isPosIn row col span andalso isSmallerThan span (getSpan acc)
+                                   then (Exp (k, span), env)
+                                   else acc,
+                          sgn_item = fn (env, (k, span), acc) =>
+                                        if isPosIn row col span andalso isSmallerThan span (getSpan acc)
+                                        then (Sgn_item (k, span), env)
+                                        else acc,
+                          sgn = fn (env, (k, span), acc) =>
+                                   if isPosIn row col span andalso isSmallerThan span (getSpan acc)
+                                   then (Sgn (k, span), env)
+                                   else acc,
+                          str = fn (env, (k, span), acc) =>
+                                   if isPosIn row col span andalso isSmallerThan span (getSpan acc)
+                                   then (Str (k, span), env)
+                                   else acc,
+                          decl = fn (env, (k, span), acc) =>
+                                    if isPosIn row col span andalso isSmallerThan span (getSpan acc)
+                                    then (Decl (k, span), env)
+                                    else acc,
+                          bind = fn (env, binder) =>
+                                    case binder of
+                                        ElabUtilPos.Decl.RelK x => 
+                                        ElabEnv.pushKRel env x
+                                      | ElabUtilPos.Decl.RelC (x, k) =>
+                                        ElabEnv.pushCRel env x k
+                                      | ElabUtilPos.Decl.NamedC (x, n, k, co) =>
+                                        ElabEnv.pushCNamedAs env x n k co
+                                      | ElabUtilPos.Decl.RelE (x, c) =>
+                                        ElabEnv.pushERel env x c
+                                      | ElabUtilPos.Decl.NamedE (x, c) => 
+                                        #1 (ElabEnv.pushENamed env x c)
+                                      | ElabUtilPos.Decl.Str (x, n, sgn) =>
+                                        #1 (ElabEnv.pushStrNamed env x sgn)
+                                      | ElabUtilPos.Decl.Sgn (x, n, sgn) =>
+                                        #1 (ElabEnv.pushSgnNamed env x sgn)
+                        }
+                        env
+                        (Decl (#1 decl, { file = file
+                                        , first = { line = 0, char = 0}
+                                        , last = { line = 99999, char = 0} })
+                        , env)
+                        decl
+            in
+                case atPosition of
+                    Kind k =>
+                    Print.box [Print.PD.string "Not implemented yet, KIND: ", ElabPrint.p_kind env k]
+                  | Con c =>
+                    Print.box [Print.PD.string "Not implemented yet, CON: ", ElabPrint.p_con env c]
+                  | Exp (Elab.EPrim p, _) =>
+                    Print.box [Prim.p_t p,
+                               Print.PD.string ": ",
+                               Print.PD.string (case p of
+                                                 Prim.Int _ => "int"
+                                               | Prim.Float _ => "float"
+                                               | Prim.String _ => "string"
+                                               | Prim.Char _ => "char")]
+                  | Exp (Elab.ERel n, _) =>
+                    ((let val found = ElabEnv.lookupERel env n
+                      in
+
+                          Print.box [ Print.PD.string (#1 found)
+                                    , Print.PD.string ": "
+                                    , ElabPrint.p_con env (#2 found)]
+                      end)
+                     handle ElabEnv.UnboundRel _ => Print.PD.string ("UNBOUND_REL" ^ Int.toString n))
+                  | Exp (Elab.ENamed n, _) =>
+                    ((let val found = ElabEnv.lookupENamed env n
+                      in
+                          Print.box [ Print.PD.string (#1 found)
+                                    , Print.PD.string ": "
+                                    , ElabPrint.p_con env (#2 found)]
+                      end)
+                     handle ElabEnv.UnboundNamed _ => Print.PD.string ("UNBOUND_NAMED" ^ Int.toString n))
+                  | Exp (Elab.EModProj ( m1 (* number (= "name") of top level module *)
+                                       , ms (* names of submodules - possibly none *)
+                                       , x (* identifier *)), loc) =>
+                    (let
+                        val (m1name, m1sgn) = ElabEnv.lookupStrNamed env m1
+                        val (str, sgn) = foldl (fn (m, (str, sgn)) =>
+                                                   case ElabEnv.projectStr env {sgn = sgn, str = str, field = m} of
+                                                       NONE => raise Fail ("Couldn't find Structure: " ^ m)
+                                                     | SOME sgn => ((Elab.StrProj (str, m), loc), sgn))
+                                               ((Elab.StrVar m1, loc), m1sgn)
+                                               ms
+                        val t = case ElabEnv.projectVal env {sgn = sgn, str = str, field = x} of
+                                    NONE => raise Fail ("Couldn't find identifier: " ^ x)
+                                  | SOME t => t
+                    in
+                        Print.box [ Print.p_list_sep (Print.PD.string ".") Print.PD.string (m1name :: ms @ [x])
+                                  , Print.PD.string ": "
+                                  , ElabPrint.p_con env t
+                                  ]
+                    end
+                     handle ElabEnv.UnboundNamed _ => Print.PD.string ("Module not found: " ^ Int.toString m1))
+                  | Exp e => Print.box [Print.PD.string "Not implemented yet, EXP: ", ElabPrint.p_exp env e]
+                  | Sgn_item si => Print.box [Print.PD.string "Not implemented yet, SGN_ITEM: ", ElabPrint.p_sgn_item env si]
+                  | Sgn s => Print.box [Print.PD.string "Not implemented yet, SGN: ", ElabPrint.p_sgn env s]
+                  | Str s => Print.box [Print.PD.string "Not implemented yet, STR: ", ElabPrint.p_str env s]
+                  | Decl d => Print.box [Print.PD.string "Not implemented yet, DECL: ", ElabPrint.p_decl env d]
+            end
+
+
+fun typeOf loc =
+    case String.tokens (fn ch => ch = #":") loc of
+        file :: rowStr :: colStr :: nil =>
+        (case (Int.fromString rowStr, Int.fromString colStr) of
+             (SOME row, SOME col) =>
+             Print.box [getTypeAt file row col, Print.PD.string "\n"]
+           | _ => Print.PD.string "ERROR: Wrong typeOf input format, should be <file:row:col>")
+      | _ => Print.PD.string "ERROR: Wrong typeOf input format, should be <file:row:col>"
 end
diff --git a/src/elab_util_pos.sig b/src/elab_util_pos.sig
new file mode 100644
index 00000000..f616f7f3
--- /dev/null
+++ b/src/elab_util_pos.sig
@@ -0,0 +1,63 @@
+(* Copyright (c) 2008-2010, 2012, Adam Chlipala
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * - The names of contributors may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *)
+
+signature ELAB_UTIL_POS = sig 
+    
+    val mliftConInCon : (int -> Elab.con -> Elab.con) ref
+
+    structure Decl : sig 
+                  datatype binder =
+                           RelK of string
+                           | RelC of string * Elab.kind
+                           | NamedC of string * int * Elab.kind * Elab.con option
+                           | RelE of string * Elab.con
+                           | NamedE of string * Elab.con
+                           | Str of string * int * Elab.sgn
+                           | Sgn of string * int * Elab.sgn
+                  
+                  val fold : {kind : Elab.kind * 'state -> 'state,
+                              con : Elab.con * 'state -> 'state,
+                              exp : Elab.exp * 'state -> 'state,
+                              sgn_item : Elab.sgn_item * 'state -> 'state,
+                              sgn : Elab.sgn * 'state -> 'state,
+                              str : Elab.str * 'state -> 'state,
+                              decl : Elab.decl * 'state -> 'state}
+                             -> 'state -> Elab.decl -> 'state
+
+                  val foldB : {kind : 'context * Elab.kind * 'state -> 'state,
+                              con : 'context * Elab.con * 'state -> 'state,
+                              exp : 'context * Elab.exp * 'state -> 'state,
+                              sgn_item : 'context * Elab.sgn_item * 'state -> 'state,
+                              sgn : 'context * Elab.sgn * 'state -> 'state,
+                              str : 'context * Elab.str * 'state -> 'state,
+                              decl : 'context * Elab.decl * 'state -> 'state,
+                              bind: 'context * binder -> 'context
+                              }
+                             -> 'context -> 'state -> Elab.decl -> 'state
+              end
+
+end
diff --git a/src/elab_util_pos.sml b/src/elab_util_pos.sml
new file mode 100644
index 00000000..d8d1bfdd
--- /dev/null
+++ b/src/elab_util_pos.sml
@@ -0,0 +1,910 @@
+(* Copyright (c) 2008-2010, Adam Chlipala
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * - The names of contributors may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *)
+
+structure ElabUtilPos :> ELAB_UTIL_POS = struct
+
+open Elab
+
+structure S = Search
+
+structure Kind = struct
+
+fun mapfoldB {kind, bind} =
+    let
+        fun mfk ctx k acc =
+            S.bindPWithPos (mfk' ctx k acc, kind ctx)
+
+        and mfk' ctx (kAll as (k, loc)) =
+            case k of
+                KType => S.return2 kAll
+
+              | KArrow (k1, k2) =>
+                S.bind2 (mfk ctx k1,
+                      fn k1' =>
+                         S.map2 (mfk ctx k2,
+                              fn k2' =>
+                                 (KArrow (k1', k2'), loc)))
+
+              | KName => S.return2 kAll
+
+              | KRecord k =>
+                S.map2 (mfk ctx k,
+                        fn k' =>
+                           (KRecord k', loc))
+
+              | KUnit => S.return2 kAll
+
+              | KTuple ks =>
+                S.map2 (ListUtil.mapfold (mfk ctx) ks,
+                        fn ks' =>
+                           (KTuple ks', loc))
+
+              | KError => S.return2 kAll
+
+              | KUnif (_, _, ref (KKnown k)) => mfk' ctx k
+              | KUnif _ => S.return2 kAll
+
+              | KTupleUnif (_, _, ref (KKnown k)) => mfk' ctx k
+              | KTupleUnif (loc, nks, r) =>
+                S.map2 (ListUtil.mapfold (fn (n, k) =>
+                                             S.map2 (mfk ctx k,
+                                                  fn k' =>
+                                                     (n, k'))) nks,
+                     fn nks' =>
+                        (KTupleUnif (loc, nks', r), loc))
+
+
+              | KRel _ => S.return2 kAll
+              | KFun (x, k) =>
+                S.map2 (mfk (bind (ctx, x)) k,
+                        fn k' =>
+                           (KFun (x, k'), loc))
+    in
+        mfk
+    end
+
+end
+
+val mliftConInCon = ref (fn n : int => fn c : con => (raise Fail "You didn't set ElabUtil.mliftConInCon!") : con)
+
+structure Con = struct
+
+datatype binder =
+         RelK of string
+       | RelC of string * Elab.kind
+       | NamedC of string * int * Elab.kind * Elab.con option
+
+fun mapfoldB {kind = fk, con = fc, bind} =
+    let
+        val mfk = Kind.mapfoldB {kind = fk, bind = fn (ctx, s) => bind (ctx, RelK s)}
+
+        fun mfc ctx c acc =
+            S.bindPWithPos (mfc' ctx c acc, fc ctx)
+
+        and mfc' ctx (cAll as (c, loc)) =
+            case c of
+                TFun (c1, c2) =>
+                S.bind2 (mfc ctx c1,
+                      fn c1' =>
+                         S.map2 (mfc ctx c2,
+                              fn c2' =>
+                                 (TFun (c1', c2'), loc)))
+              | TCFun (e, x, k, c) =>
+                S.bind2 (mfk ctx k,
+                      fn k' =>
+                         S.map2 (mfc (bind (ctx, RelC (x, k))) c,
+                              fn c' =>
+                                 (TCFun (e, x, k', c'), loc)))
+              | TDisjoint (c1, c2, c3) =>
+                S.bind2 (mfc ctx c1,
+                      fn c1' =>
+                         S.bind2 (mfc ctx c2,
+                              fn c2' =>
+                                 S.map2 (mfc ctx c3,
+                                         fn c3' =>
+                                            (TDisjoint (c1', c2', c3'), loc))))
+              | TRecord c =>
+                S.map2 (mfc ctx c,
+                        fn c' =>
+                           (TRecord c', loc))
+
+              | CRel _ => S.return2 cAll
+              | CNamed _ => S.return2 cAll
+              | CModProj _ => S.return2 cAll
+              | CApp (c1, c2) =>
+                S.bind2 (mfc ctx c1,
+                      fn c1' =>
+                         S.map2 (mfc ctx c2,
+                              fn c2' =>
+                                 (CApp (c1', c2'), loc)))
+              | CAbs (x, k, c) =>
+                S.bind2 (mfk ctx k,
+                      fn k' =>
+                         S.map2 (mfc (bind (ctx, RelC (x, k))) c,
+                              fn c' =>
+                                 (CAbs (x, k', c'), loc)))
+
+              | CName _ => S.return2 cAll
+
+              | CRecord (k, xcs) =>
+                S.bind2 (mfk ctx k,
+                      fn k' =>
+                         S.map2 (ListUtil.mapfold (fn (x, c) =>
+                                                      S.bind2 (mfc ctx x,
+                                                            fn x' =>
+                                                               S.map2 (mfc ctx c,
+                                                                    fn c' =>
+                                                                       (x', c'))))
+                                 xcs,
+                              fn xcs' =>
+                                 (CRecord (k', xcs'), loc)))
+              | CConcat (c1, c2) =>
+                S.bind2 (mfc ctx c1,
+                      fn c1' =>
+                         S.map2 (mfc ctx c2,
+                              fn c2' =>
+                                 (CConcat (c1', c2'), loc)))
+              | CMap (k1, k2) =>
+                S.bind2 (mfk ctx k1,
+                         fn k1' =>
+                            S.map2 (mfk ctx k2,
+                                    fn k2' =>
+                                       (CMap (k1', k2'), loc)))
+
+              | CUnit => S.return2 cAll
+
+              | CTuple cs =>
+                S.map2 (ListUtil.mapfold (mfc ctx) cs,
+                        fn cs' =>
+                           (CTuple cs', loc))
+
+              | CProj (c, n) =>
+                S.map2 (mfc ctx c,
+                        fn c' =>
+                           (CProj (c', n), loc))
+
+              | CError => S.return2 cAll
+              | CUnif (nl, _, _, _, ref (Known c)) => mfc' ctx (!mliftConInCon nl c)
+              | CUnif _ => S.return2 cAll
+                        
+              | CKAbs (x, c) =>
+                S.map2 (mfc (bind (ctx, RelK x)) c,
+                        fn c' =>
+                           (CKAbs (x, c'), loc))
+              | CKApp (c, k) =>
+                S.bind2 (mfc ctx c,
+                      fn c' =>
+                         S.map2 (mfk ctx k,
+                                 fn k' =>
+                                    (CKApp (c', k'), loc)))
+              | TKFun (x, c) =>
+                S.map2 (mfc (bind (ctx, RelK x)) c,
+                        fn c' =>
+                           (TKFun (x, c'), loc))
+    in
+        mfc
+    end
+
+end
+
+structure Exp = struct
+
+datatype binder =
+         RelK of string
+       | RelC of string * Elab.kind
+       | NamedC of string * int * Elab.kind * Elab.con option
+       | RelE of string * Elab.con
+       | NamedE of string * Elab.con
+
+fun mapfoldB {kind = fk, con = fc, exp = fe, bind} =
+    let
+        val mfk = Kind.mapfoldB {kind = fk, bind = fn (ctx, x) => bind (ctx, RelK x)}
+
+        fun bind' (ctx, b) =
+            let
+                val b' = case b of
+                             Con.RelK x => RelK x
+                           | Con.RelC x => RelC x
+                           | Con.NamedC x => NamedC x
+            in
+                bind (ctx, b')
+            end
+        val mfc = Con.mapfoldB {kind = fk, con = fc, bind = bind'}
+
+        fun doVars ((p, _), ctx) =
+            case p of
+                PVar xt => bind (ctx, RelE xt)
+              | PPrim _ => ctx
+              | PCon (_, _, _, NONE) => ctx
+              | PCon (_, _, _, SOME p) => doVars (p, ctx)
+              | PRecord xpcs =>
+                foldl (fn ((_, p, _), ctx) => doVars (p, ctx))
+                      ctx xpcs
+
+        fun mfe ctx e acc =
+            S.bindPWithPos (mfe' ctx e acc, fe ctx)
+
+        and mfe' ctx (eAll as (e, loc)) =
+            case e of
+                EPrim _ => S.return2 eAll
+              | ERel _ => S.return2 eAll
+              | ENamed _ => S.return2 eAll
+              | EModProj _ => S.return2 eAll
+              | EApp (e1, e2) =>
+                S.bind2 (mfe ctx e1,
+                      fn e1' =>
+                         S.map2 (mfe ctx e2,
+                              fn e2' =>
+                                 (EApp (e1', e2'), loc)))
+              | EAbs (x, dom, ran, e) =>
+                S.bind2 (mfc ctx dom,
+                      fn dom' =>
+                         S.bind2 (mfc ctx ran,
+                                  fn ran' =>
+                                     S.map2 (mfe (bind (ctx, RelE (x, dom'))) e,
+                                          fn e' =>
+                                             (EAbs (x, dom', ran', e'), loc))))
+                         
+              | ECApp (e, c) =>
+                S.bind2 (mfe ctx e,
+                      fn e' =>
+                         S.map2 (mfc ctx c,
+                              fn c' =>
+                                 (ECApp (e', c'), loc)))
+              | ECAbs (expl, x, k, e) =>
+                S.bind2 (mfk ctx k,
+                      fn k' =>
+                         S.map2 (mfe (bind (ctx, RelC (x, k))) e,
+                              fn e' =>
+                                 (ECAbs (expl, x, k', e'), loc)))
+
+              | ERecord xes =>
+                S.map2 (ListUtil.mapfold (fn (x, e, t) =>
+                                             S.bind2 (mfc ctx x,
+                                                   fn x' =>
+                                                      S.bind2 (mfe ctx e,
+                                                           fn e' =>
+                                                              S.map2 (mfc ctx t,
+                                                                   fn t' =>
+                                                                      (x', e', t')))))
+                                         xes,
+                     fn xes' =>
+                        (ERecord xes', loc))
+              | EField (e, c, {field, rest}) =>
+                S.bind2 (mfe ctx e,
+                      fn e' =>
+                         S.bind2 (mfc ctx c,
+                              fn c' =>
+                                 S.bind2 (mfc ctx field,
+                                          fn field' =>
+                                             S.map2 (mfc ctx rest,
+                                                  fn rest' =>
+                                                     (EField (e', c', {field = field', rest = rest'}), loc)))))
+              | EConcat (e1, c1, e2, c2) =>
+                S.bind2 (mfe ctx e1,
+                      fn e1' =>
+                         S.bind2 (mfc ctx c1,
+                              fn c1' =>
+                                 S.bind2 (mfe ctx e2,
+                                       fn e2' =>
+                                          S.map2 (mfc ctx c2,
+                                               fn c2' =>
+                                                  (EConcat (e1', c1', e2', c2'),
+                                                   loc)))))
+              | ECut (e, c, {field, rest}) =>
+                S.bind2 (mfe ctx e,
+                      fn e' =>
+                         S.bind2 (mfc ctx c,
+                              fn c' =>
+                                 S.bind2 (mfc ctx field,
+                                          fn field' =>
+                                             S.map2 (mfc ctx rest,
+                                                  fn rest' =>
+                                                     (ECut (e', c', {field = field', rest = rest'}), loc)))))
+
+              | ECutMulti (e, c, {rest}) =>
+                S.bind2 (mfe ctx e,
+                      fn e' =>
+                         S.bind2 (mfc ctx c,
+                              fn c' =>
+                                 S.map2 (mfc ctx rest,
+                                      fn rest' =>
+                                         (ECutMulti (e', c', {rest = rest'}), loc))))
+
+              | ECase (e, pes, {disc, result}) =>
+                S.bind2 (mfe ctx e,
+                         fn e' =>
+                            S.bind2 (ListUtil.mapfold (fn (p, e) =>
+                                                          let
+                                                              fun pb ((p, _), ctx) =
+                                                                  case p of
+                                                                      PVar (x, t) => bind (ctx, RelE (x, t))
+                                                                    | PPrim _ => ctx
+                                                                    | PCon (_, _, _, NONE) => ctx
+                                                                    | PCon (_, _, _, SOME p) => pb (p, ctx)
+                                                                    | PRecord xps => foldl (fn ((_, p, _), ctx) =>
+                                                                                               pb (p, ctx)) ctx xps
+                                                          in
+                                                              S.bind2 (mfp ctx p,
+                                                                       fn p' =>
+                                                                          S.map2 (mfe (pb (p', ctx)) e,
+                                                                               fn e' => (p', e')))
+                                                          end) pes,
+                                    fn pes' =>
+                                       S.bind2 (mfc ctx disc,
+                                             fn disc' =>
+                                                S.map2 (mfc ctx result,
+                                                     fn result' =>
+                                                        (ECase (e', pes', {disc = disc', result = result'}), loc)))))
+
+              | EError => S.return2 eAll
+              | EUnif (ref (SOME e)) => mfe ctx e
+              | EUnif _ => S.return2 eAll
+
+              | ELet (des, e, t) =>
+                let
+                    val (des, ctx') = foldl (fn (ed, (des, ctx)) =>
+                                                let
+                                                    val ctx' =
+                                                        case #1 ed of
+                                                            EDVal (p, _, _) => doVars (p, ctx)
+                                                          | EDValRec vis =>
+                                                            foldl (fn ((x, t, _), ctx) => bind (ctx, RelE (x, t)))
+                                                                  ctx vis
+                                                in
+                                                    (S.bind2 (des,
+                                                           fn des' =>
+                                                              S.map2 (mfed ctx ed,
+                                                                   fn ed' => ed' :: des')),
+                                                     ctx')
+                                                end)
+                                            (S.return2 [], ctx) des
+                in
+                    S.bind2 (des,
+                         fn des' =>
+                            S.bind2 (mfe ctx' e,
+                                    fn e' =>
+                                       S.map2 (mfc ctx t,
+                                               fn t' =>
+                                                  (ELet (rev des', e', t'), loc))))
+                end
+
+              | EKAbs (x, e) =>
+                S.map2 (mfe (bind (ctx, RelK x)) e,
+                        fn e' =>
+                           (EKAbs (x, e'), loc))
+              | EKApp (e, k) =>
+                S.bind2 (mfe ctx e,
+                        fn e' =>
+                           S.map2 (mfk ctx k,
+                                   fn k' =>
+                                      (EKApp (e', k'), loc)))
+
+        and mfp ctx (pAll as (p, loc)) =
+            case p of
+                PVar (x, t) =>
+                S.map2 (mfc ctx t,
+                        fn t' =>
+                           (PVar (x, t'), loc))
+              | PPrim _ => S.return2 pAll
+              | PCon (dk, pc, args, po) =>
+                S.bind2 (ListUtil.mapfold (mfc ctx) args,
+                      fn args' =>
+                         S.map2 ((case po of
+                                      NONE => S.return2 NONE
+                                    | SOME p => S.map2 (mfp ctx p, SOME)),
+                              fn po' =>
+                                 (PCon (dk, pc, args', po'), loc)))
+              | PRecord xps =>
+                S.map2 (ListUtil.mapfold (fn (x, p, c) =>
+                                              S.bind2 (mfp ctx p,
+                                                       fn p' =>
+                                                          S.map2 (mfc ctx c,
+                                                                  fn c' =>
+                                                                     (x, p', c')))) xps,
+                         fn xps' =>
+                            (PRecord xps', loc))
+
+        and mfed ctx (dAll as (d, loc)) =
+            case d of
+                EDVal (p, t, e) =>
+                S.bind2 (mfc ctx t,
+                         fn t' =>
+                            S.map2 (mfe ctx e,
+                                 fn e' =>
+                                    (EDVal (p, t', e'), loc)))
+              | EDValRec vis =>
+                let
+                    val ctx = foldl (fn ((x, t, _), ctx) => bind (ctx, RelE (x, t))) ctx vis
+                in
+                    S.map2 (ListUtil.mapfold (mfvi ctx) vis,
+                         fn vis' =>
+                            (EDValRec vis', loc))
+                end
+
+        and mfvi ctx (x, c, e) =
+            S.bind2 (mfc ctx c,
+                  fn c' =>
+                     S.map2 (mfe ctx e,
+                          fn e' =>
+                             (x, c', e')))
+    in
+        mfe
+    end
+
+end
+
+structure Sgn = struct
+
+datatype binder =
+         RelK of string
+       | RelC of string * Elab.kind
+       | NamedC of string * int * Elab.kind * Elab.con option
+       | Str of string * int * Elab.sgn
+       | Sgn of string * int * Elab.sgn
+
+fun mapfoldB {kind, con, sgn_item, sgn, bind} =
+    let
+        fun bind' (ctx, b) =
+            let
+                val b' = case b of
+                             Con.RelK x => RelK x
+                           | Con.RelC x => RelC x
+                           | Con.NamedC x => NamedC x
+            in
+                bind (ctx, b')
+            end
+        val con = Con.mapfoldB {kind = kind, con = con, bind = bind'}
+
+        val kind = Kind.mapfoldB {kind = kind, bind = fn (ctx, x) => bind (ctx, RelK x)}
+
+        fun sgi ctx si acc =
+            S.bindPWithPos (sgi' ctx si acc, sgn_item ctx)
+
+        and sgi' ctx (siAll as (si, loc)) =
+            case si of
+                SgiConAbs (x, n, k) =>
+                S.map2 (kind ctx k,
+                     fn k' =>
+                        (SgiConAbs (x, n, k'), loc))
+              | SgiCon (x, n, k, c) =>
+                S.bind2 (kind ctx k,
+                     fn k' =>
+                        S.map2 (con ctx c,
+                             fn c' =>
+                                (SgiCon (x, n, k', c'), loc)))
+              | SgiDatatype dts =>
+                S.map2 (ListUtil.mapfold (fn (x, n, xs, xncs) =>
+                                             S.map2 (ListUtil.mapfold (fn (x, n, c) =>
+                                                                          case c of
+                                                                              NONE => S.return2 (x, n, c)
+                                                                            | SOME c =>
+                                                                              S.map2 (con ctx c,
+                                                                                   fn c' => (x, n, SOME c'))) xncs,
+                                                  fn xncs' => (x, n, xs, xncs'))) dts,
+                        fn dts' =>
+                           (SgiDatatype dts', loc))
+              | SgiDatatypeImp (x, n, m1, ms, s, xs, xncs) =>
+                S.map2 (ListUtil.mapfold (fn (x, n, c) =>
+                                             case c of
+                                                 NONE => S.return2 (x, n, c)
+                                               | SOME c =>
+                                                 S.map2 (con ctx c,
+                                                      fn c' => (x, n, SOME c'))) xncs,
+                        fn xncs' =>
+                           (SgiDatatypeImp (x, n, m1, ms, s, xs, xncs'), loc))
+              | SgiVal (x, n, c) =>
+                S.map2 (con ctx c,
+                     fn c' =>
+                        (SgiVal (x, n, c'), loc))
+              | SgiStr (im, x, n, s) =>
+                S.map2 (sg ctx s,
+                     fn s' =>
+                        (SgiStr (im, x, n, s'), loc))
+              | SgiSgn (x, n, s) =>
+                S.map2 (sg ctx s,
+                     fn s' =>
+                        (SgiSgn (x, n, s'), loc))
+              | SgiConstraint (c1, c2) =>
+                S.bind2 (con ctx c1,
+                         fn c1' =>
+                            S.map2 (con ctx c2,
+                                    fn c2' =>
+                                       (SgiConstraint (c1', c2'), loc)))
+              | SgiClassAbs (x, n, k) =>
+                S.map2 (kind ctx k,
+                        fn k' =>
+                           (SgiClassAbs (x, n, k'), loc))
+              | SgiClass (x, n, k, c) =>
+                S.bind2 (kind ctx k,
+                      fn k' => 
+                         S.map2 (con ctx c,
+                              fn c' =>
+                                 (SgiClass (x, n, k', c'), loc)))
+
+        and sg ctx s acc =
+            S.bindPWithPos (sg' ctx s acc, sgn ctx)
+
+        and sg' ctx (sAll as (s, loc)) =
+            case s of
+                SgnConst sgis =>
+                S.map2 (ListUtil.mapfoldB (fn (ctx, si)  =>
+                                              (case #1 si of
+                                                   SgiConAbs (x, n, k) =>
+                                                   bind (ctx, NamedC (x, n, k, NONE))
+                                                 | SgiCon (x, n, k, c) =>
+                                                   bind (ctx, NamedC (x, n, k, SOME c))
+                                                 | SgiDatatype dts =>
+                                                   foldl (fn ((x, n, ks, _), ctx) =>
+                                                             let
+                                                                 val k' = (KType, loc)
+                                                                 val k = foldl (fn (_, k) => (KArrow (k', k), loc))
+                                                                               k' ks
+                                                             in
+                                                                 bind (ctx, NamedC (x, n, k, NONE))
+                                                             end) ctx dts
+                                                 | SgiDatatypeImp (x, n, m1, ms, s, _, _) =>
+                                                   bind (ctx, NamedC (x, n, (KType, loc),
+                                                                      SOME (CModProj (m1, ms, s), loc)))
+                                                 | SgiVal _ => ctx
+                                                 | SgiStr (_, x, n, sgn) =>
+                                                   bind (ctx, Str (x, n, sgn))
+                                                 | SgiSgn (x, n, sgn) =>
+                                                   bind (ctx, Sgn (x, n, sgn))
+                                                 | SgiConstraint _ => ctx
+                                                 | SgiClassAbs (x, n, k) =>
+                                                   bind (ctx, NamedC (x, n, (KArrow (k, (KType, loc)), loc), NONE))
+                                                 | SgiClass (x, n, k, c) =>
+                                                   bind (ctx, NamedC (x, n, (KArrow (k, (KType, loc)), loc), SOME c)),
+                                               sgi ctx si)) ctx sgis,
+                     fn sgis' =>
+                        (SgnConst sgis', loc))
+                
+              | SgnVar _ => S.return2 sAll
+              | SgnFun (m, n, s1, s2) =>
+                S.bind2 (sg ctx s1,
+                         fn s1' =>
+                            S.map2 (sg (bind (ctx, Str (m, n, s1'))) s2,
+                                    fn s2' =>
+                                       (SgnFun (m, n, s1', s2'), loc)))
+              | SgnProj _ => S.return2 sAll
+              | SgnWhere (sgn, ms, x, c) =>
+                S.bind2 (sg ctx sgn,
+                      fn sgn' =>
+                         S.map2 (con ctx c,
+                              fn c' =>
+                                 (SgnWhere (sgn', ms, x, c'), loc)))
+              | SgnError => S.return2 sAll
+    in
+        sg
+    end
+
+end
+
+structure Decl = struct
+
+datatype binder =
+         RelK of string
+       | RelC of string * Elab.kind
+       | NamedC of string * int * Elab.kind * Elab.con option
+       | RelE of string * Elab.con
+       | NamedE of string * Elab.con
+       | Str of string * int * Elab.sgn
+       | Sgn of string * int * Elab.sgn
+
+fun mapfoldB {kind = fk, con = fc, exp = fe, sgn_item = fsgi, sgn = fsg, str = fst, decl = fd, bind} =
+    let
+        val mfk = Kind.mapfoldB {kind = fk, bind = fn (ctx, x) => bind (ctx, RelK x)}
+
+        fun bind' (ctx, b) =
+            let
+                val b' = case b of
+                             Con.RelK x => RelK x
+                           | Con.RelC x => RelC x
+                           | Con.NamedC x => NamedC x
+            in
+                bind (ctx, b')
+            end
+        val mfc = Con.mapfoldB {kind = fk, con = fc, bind = bind'}
+
+        fun bind' (ctx, b) =
+            let
+                val b' = case b of
+                             Exp.RelK x => RelK x
+                           | Exp.RelC x => RelC x
+                           | Exp.NamedC x => NamedC x
+                           | Exp.RelE x => RelE x
+                           | Exp.NamedE x => NamedE x
+            in
+                bind (ctx, b')
+            end
+        val mfe = Exp.mapfoldB {kind = fk, con = fc, exp = fe, bind = bind'}
+
+        fun bind' (ctx, b) =
+            let
+                val b' = case b of
+                             Sgn.RelK x => RelK x
+                           | Sgn.RelC x => RelC x
+                           | Sgn.NamedC x => NamedC x
+                           | Sgn.Sgn x => Sgn x
+                           | Sgn.Str x => Str x
+            in
+                bind (ctx, b')
+            end
+        val mfsg = Sgn.mapfoldB {kind = fk, con = fc, sgn_item = fsgi, sgn = fsg, bind = bind'}
+
+        fun mfst ctx str acc =
+            S.bindPWithPos (mfst' ctx str acc, fst ctx)
+
+        and mfst' ctx (strAll as (str, loc)) =
+            case str of
+                StrConst ds => 
+                S.map2 (ListUtil.mapfoldB (fn (ctx, d)  =>
+                                              (case #1 d of
+                                                   DCon (x, n, k, c) =>
+                                                   bind (ctx, NamedC (x, n, k, SOME c))
+                                                 | DDatatype dts =>
+                                                   let
+                                                       fun doOne ((x, n, xs, xncs), ctx) =
+                                                           let
+                                                               val ctx = bind (ctx, NamedC (x, n, (KType, loc), NONE))
+                                                           in
+                                                               foldl (fn ((x, _, co), ctx) =>
+                                                                         let
+                                                                             val t =
+                                                                                 case co of
+                                                                                     NONE => CNamed n
+                                                                                   | SOME t => TFun (t, (CNamed n, loc))
+                                                                                               
+                                                                             val k = (KType, loc)
+                                                                             val t = (t, loc)
+                                                                             val t = foldr (fn (x, t) =>
+                                                                                               (TCFun (Explicit,
+                                                                                                       x,
+                                                                                                       k,
+                                                                                                       t), loc))
+                                                                                           t xs
+                                                                         in
+                                                                             bind (ctx, NamedE (x, t))
+                                                                         end)
+                                                                     ctx xncs
+                                                           end
+                                                   in
+                                                       foldl doOne ctx dts
+                                                   end
+                                                 | DDatatypeImp (x, n, m, ms, x', _, _) =>
+                                                   bind (ctx, NamedC (x, n, (KType, loc),
+                                                                      SOME (CModProj (m, ms, x'), loc)))
+                                                 | DVal (x, _, c, _) =>
+                                                   bind (ctx, NamedE (x, c))
+                                                 | DValRec vis =>
+                                                   foldl (fn ((x, _, c, _), ctx) => bind (ctx, NamedE (x, c))) ctx vis
+                                                 | DSgn (x, n, sgn) =>
+                                                   bind (ctx, Sgn (x, n, sgn))
+                                                 | DStr (x, n, sgn, _) =>
+                                                   bind (ctx, Str (x, n, sgn))
+                                                 | DFfiStr (x, n, sgn) =>
+                                                   bind (ctx, Str (x, n, sgn))
+                                                 | DConstraint _ => ctx
+                                                 | DExport _ => ctx
+                                                 | DTable (tn, x, n, c, _, pc, _, cc) =>
+                                                   let
+                                                       val ct = (CModProj (n, [], "sql_table"), loc)
+                                                       val ct = (CApp (ct, c), loc)
+                                                       val ct = (CApp (ct, (CConcat (pc, cc), loc)), loc)
+                                                   in
+                                                       bind (ctx, NamedE (x, ct))
+                                                   end
+                                                 | DSequence (tn, x, n) =>
+                                                   bind (ctx, NamedE (x, (CModProj (n, [], "sql_sequence"), loc)))
+                                                 | DView (tn, x, n, _, c) =>
+                                                   let
+                                                       val ct = (CModProj (n, [], "sql_view"), loc)
+                                                       val ct = (CApp (ct, c), loc)
+                                                   in
+                                                       bind (ctx, NamedE (x, ct))
+                                                   end
+                                                 | DDatabase _ => ctx
+                                                 | DCookie (tn, x, n, c) =>
+                                                   bind (ctx, NamedE (x, (CApp ((CModProj (n, [], "cookie"), loc),
+                                                                                c), loc)))
+                                                 | DStyle (tn, x, n) =>
+                                                   bind (ctx, NamedE (x, (CModProj (n, [], "css_class"), loc)))
+                                                 | DTask _ => ctx
+                                                 | DPolicy _ => 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
+              | StrProj (str, x) =>
+                S.map2 (mfst ctx str,
+                        fn str' =>
+                           (StrProj (str', x), loc))
+              | StrFun (x, n, sgn1, sgn2, str) =>
+                S.bind2 (mfsg ctx sgn1,
+                         fn sgn1' =>
+                            S.bind2 (mfsg ctx sgn2,
+                                     fn sgn2' =>
+                                        S.map2 (mfst ctx str,
+                                                fn str' =>
+                                                   (StrFun (x, n, sgn1', sgn2', str'), loc))))
+              | StrApp (str1, str2) =>
+                S.bind2 (mfst ctx str1,
+                         fn str1' =>
+                            S.map2 (mfst ctx str2,
+                                    fn str2' =>
+                                       (StrApp (str1', str2'), loc)))
+              | StrError => S.return2 strAll
+
+        and mfd ctx d acc =
+            S.bindPWithPos (mfd' ctx d acc, fd ctx)
+
+        and mfd' ctx (dAll as (d, loc)) =
+            case d of
+                DCon (x, n, k, c) =>
+                S.bind2 (mfk ctx k,
+                         fn k' =>
+                            S.map2 (mfc ctx c,
+                                    fn c' =>
+                                       (DCon (x, n, k', c'), loc)))
+              | DDatatype dts =>
+                S.map2 (ListUtil.mapfold (fn (x, n, xs, xncs) =>
+                                             S.map2 (ListUtil.mapfold (fn (x, n, c) =>
+                                                                          case c of
+                                                                              NONE => S.return2 (x, n, c)
+                                                                            | SOME c =>
+                                                                              S.map2 (mfc ctx c,
+                                                                                   fn c' => (x, n, SOME c'))) xncs,
+                                                     fn xncs' =>
+                                                        (x, n, xs, xncs'))) dts,
+                     fn dts' =>
+                        (DDatatype dts', loc))
+              | DDatatypeImp (x, n, m1, ms, s, xs, xncs) =>
+                S.map2 (ListUtil.mapfold (fn (x, n, c) =>
+                                             case c of
+                                                 NONE => S.return2 (x, n, c)
+                                               | SOME c =>
+                                                 S.map2 (mfc ctx c,
+                                                      fn c' => (x, n, SOME c'))) xncs,
+                        fn xncs' =>
+                           (DDatatypeImp (x, n, m1, ms, s, xs, xncs'), loc))
+              | DVal vi =>
+                S.map2 (mfvi ctx vi,
+                     fn vi' =>
+                        (DVal vi', loc))
+              | DValRec vis =>
+                S.map2 (ListUtil.mapfold (mfvi ctx) vis,
+                     fn vis' =>
+                        (DValRec vis', loc))
+              | DSgn (x, n, sgn) =>
+                S.map2 (mfsg ctx sgn,
+                        fn sgn' =>
+                           (DSgn (x, n, sgn'), loc))
+              | DStr (x, n, sgn, str) =>
+                S.bind2 (mfsg ctx sgn,
+                         fn sgn' =>
+                            S.map2 (mfst ctx str,
+                                    fn str' =>
+                                       (DStr (x, n, sgn', str'), loc)))
+              | DFfiStr (x, n, sgn) =>
+                S.map2 (mfsg ctx sgn,
+                        fn sgn' =>
+                           (DFfiStr (x, n, sgn'), loc))
+              | DConstraint (c1, c2) =>
+                S.bind2 (mfc ctx c1,
+                         fn c1' =>
+                            S.map2 (mfc ctx c2,
+                                    fn c2' =>
+                                       (DConstraint (c1', c2'), loc)))
+              | DExport (en, sgn, str) =>
+                S.bind2 (mfsg ctx sgn,
+                         fn sgn' =>
+                            S.map2 (mfst ctx str,
+                                    fn str' =>
+                                       (DExport (en, sgn', str'), loc)))
+
+              | DTable (tn, x, n, c, pe, pc, ce, cc) =>
+                S.bind2 (mfc ctx c,
+                        fn c' =>
+                           S.bind2 (mfe ctx pe,
+                                   fn pe' =>
+                                      S.bind2 (mfc ctx pc,
+                                            fn pc' =>
+                                               S.bind2 (mfe ctx ce,
+                                                     fn ce' =>
+                                                        S.map2 (mfc ctx cc,
+                                                              fn cc' =>
+                                                                 (DTable (tn, x, n, c', pe', pc', ce', cc'), loc))))))
+              | DSequence _ => S.return2 dAll
+              | DView (tn, x, n, e, c) =>
+                S.bind2 (mfe ctx e,
+                        fn e' =>
+                           S.map2 (mfc ctx c,
+                                   fn c' =>
+                                      (DView (tn, x, n, e', c'), loc)))
+
+              | DDatabase _ => S.return2 dAll
+
+              | DCookie (tn, x, n, c) =>
+                S.map2 (mfc ctx c,
+                        fn c' =>
+                           (DCookie (tn, x, n, c'), loc))
+              | DStyle _ => S.return2 dAll
+              | DTask (e1, e2) =>
+                S.bind2 (mfe ctx e1,
+                        fn e1' =>
+                           S.map2 (mfe ctx e2,
+                                fn e2' =>
+                                   (DTask (e1', e2'), loc)))
+              | DPolicy e1 =>
+                S.map2 (mfe ctx e1,
+                     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,
+                  fn c' =>
+                     S.map2 (mfe ctx e,
+                          fn e' =>
+                             (x, n, c', e')))
+    in
+        mfd
+    end
+
+    fun fold {kind, con, exp, sgn_item, sgn, str, decl} (st : 'a) d : 'a =
+        case mapfoldB {kind = fn () => fn k => fn st => S.Continue (#1 k, kind (k, st)),
+                      con = fn () => fn c => fn st => S.Continue (#1 c, con (c, st)),
+                      exp = fn () => fn e => fn st => S.Continue (#1 e, exp (e, st)),
+                      sgn_item = fn () => fn sgi => fn st => S.Continue (#1 sgi, sgn_item (sgi, st)),
+                      sgn = fn () => fn s => fn st => S.Continue (#1 s, sgn (s, st)),
+                      str = fn () => fn str' => fn st => S.Continue (#1 str', str (str', st)),
+                      decl = fn () => fn d => fn st => S.Continue (#1 d, decl (d, st)),
+                      bind = fn ((), _) => ()
+                      } () d st of
+            S.Continue (_, st) => st
+          | S.Return _ => raise Fail "ElabUtil.Decl.fold: Impossible"
+
+    fun foldB {kind, con, exp, sgn_item, sgn, str, decl, bind} ctx (st : 'a) d : 'a =
+        case mapfoldB {kind = fn ctx => fn k => fn st => S.Continue (#1 k, kind (ctx, k, st)),
+                      con = fn ctx => fn c => fn st => S.Continue (#1 c, con (ctx, c, st)),
+                      exp = fn ctx => fn e => fn st => S.Continue (#1 e, exp (ctx, e, st)),
+                      sgn_item = fn ctx => fn sgi => fn st => S.Continue (#1 sgi, sgn_item (ctx, sgi, st)),
+                      sgn = fn ctx => fn s => fn st => S.Continue (#1 s, sgn (ctx, s, st)),
+                      str = fn ctx => fn str' => fn st => S.Continue (#1 str', str (ctx, str', st)),
+                      decl = fn ctx => fn d => fn st => S.Continue (#1 d, decl (ctx, d, st)),
+                      bind = bind
+                      } ctx d st of
+            S.Continue (_, st) => st
+          | S.Return _ => raise Fail "ElabUtil.Decl.foldB: Impossible"
+    end
+end
diff --git a/src/main.mlton.sml b/src/main.mlton.sml
index cb7c8a77..8e70e398 100644
--- a/src/main.mlton.sml
+++ b/src/main.mlton.sml
@@ -139,6 +139,10 @@ fun oneRun args =
         fun printModuleOf fname =
             print_and_exit (Compiler.moduleOf fname) ()
 
+        fun typeOf loc =
+            (Print.print (Compiler.typeOf loc);
+             raise Code OS.Process.success)
+
         fun add_class (class, num) =
             case Int.fromString num of
                  NONE => raise Fail ("Invalid limit number '" ^ num ^ "'")
@@ -245,6 +249,8 @@ fun oneRun args =
                     NONE),
               ("moduleOf", ONE ("<file>", printModuleOf),
                     SOME "print module name of <file> and exit"),
+              ("typeOf", ONE ("<file:row:col>", typeOf),
+                    SOME "print type of expression at <file:row:col> and exit"),
               ("noEmacs", set_true Demo.noEmacs,
                     NONE),
               ("limit", TWO ("<class>", "<num>", add_class),
diff --git a/src/mod_db.sig b/src/mod_db.sig
index c45fd203..40cd52e2 100644
--- a/src/mod_db.sig
+++ b/src/mod_db.sig
@@ -36,6 +36,8 @@ signature MOD_DB = sig
 
     val lookup : Source.decl -> Elab.decl option
 
+    val lookupForTooling : string -> (Elab.decl * Elab.decl list) option
+
     (* Allow undoing to snapshots after failed compilations. *)
     val snapshot : unit -> unit
     val revert : unit -> unit
diff --git a/src/mod_db.sml b/src/mod_db.sml
index de428570..fdf6d5ab 100644
--- a/src/mod_db.sml
+++ b/src/mod_db.sml
@@ -207,6 +207,15 @@ fun lookup (d : Source.decl) =
                  NONE)
       | _ => NONE
 
+fun lookupForTooling name =
+    case SM.find (!byName, name) of
+        NONE => NONE
+      | SOME m =>
+        SOME (#Decl m, List.map (fn a => #Decl a)
+                                (List.mapPartial
+                                     (fn d => SM.find (!byName, d))
+                                     (SS.listItems (#Deps m))))
+
 val byNameBackup = ref (!byName)
 val byIdBackup = ref (!byId)
 
diff --git a/src/search.sig b/src/search.sig
index ac867146..2de85425 100644
--- a/src/search.sig
+++ b/src/search.sig
@@ -59,4 +59,9 @@ signature SEARCH = sig
                 * ('state11 -> 'state2 -> ('state11 * 'state2, 'abort) result)
                 -> (('state11 * 'state12) * 'state2, 'abort) result
 
+    val bindPWithPos :
+        (('state11 * 'state12) * 'state2, 'abort) result
+        * (('state11 * 'state12) -> 'state2 -> ('state11 * 'state2, 'abort) result)
+        -> (('state11 * 'state12) * 'state2, 'abort) result
+
 end
diff --git a/src/search.sml b/src/search.sml
index 563496fe..5e4e135f 100644
--- a/src/search.sml
+++ b/src/search.sml
@@ -70,4 +70,12 @@ fun bindP (r, f) =
              ((x', pos), acc'))
       | Return x => Return x
 
+fun bindPWithPos (r, f) =
+    case r of
+        Continue ((x, pos), acc) =>
+        map (f (x, pos) acc,
+             fn (x', acc') =>
+                ((x', pos), acc'))
+      | Return x => Return x
+
 end
diff --git a/src/sources b/src/sources
index 851cdc16..e25ccd2e 100644
--- a/src/sources
+++ b/src/sources
@@ -69,6 +69,9 @@ $(SRC)/elab.sml
 $(SRC)/elab_util.sig
 $(SRC)/elab_util.sml
 
+$(SRC)/elab_util_pos.sig
+$(SRC)/elab_util_pos.sml
+
 $(SRC)/elab_env.sig
 $(SRC)/elab_env.sml