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authorGravatar Adam Chlipala <adamc@hcoop.net>2009-05-03 14:57:33 -0400
committerGravatar Adam Chlipala <adamc@hcoop.net>2009-05-03 14:57:33 -0400
commite1618fb012b5926889d80893c9ac4ce08838519d (patch)
tree46b157b5c6fb6967e1ab4809f94a6d6505de7411 /lib
parentddac92a3d792b7e7342e4003862cd5ff5c1f0ab8 (diff)
outer demo
Diffstat (limited to 'lib')
-rw-r--r--lib/ur/basis.urs1
-rw-r--r--lib/ur/top.ur18
-rw-r--r--lib/ur/top.urs3
3 files changed, 22 insertions, 0 deletions
diff --git a/lib/ur/basis.urs b/lib/ur/basis.urs
index ea4432cd..9736ce1e 100644
--- a/lib/ur/basis.urs
+++ b/lib/ur/basis.urs
@@ -70,6 +70,7 @@ val read_float : read float
val read_string : read string
val read_bool : read bool
val read_time : read time
+val mkRead : t ::: Type -> (string -> t) -> (string -> option t) -> read t
(** * Monads *)
diff --git a/lib/ur/top.ur b/lib/ur/top.ur
index b9728158..f9b3d033 100644
--- a/lib/ur/top.ur
+++ b/lib/ur/top.ur
@@ -71,6 +71,24 @@ fun ex (tf :: (Type -> Type)) (choice :: Type) (body : tf choice) : ex tf =
fun compose (t1 ::: Type) (t2 ::: Type) (t3 ::: Type)
(f1 : t2 -> t3) (f2 : t1 -> t2) (x : t1) = f1 (f2 x)
+fun show_option (t ::: Type) (_ : show t) =
+ mkShow (fn opt : option t =>
+ case opt of
+ None => ""
+ | Some x => show x)
+
+fun read_option (t ::: Type) (_ : read t) =
+ mkRead (fn s =>
+ case s of
+ "" => None
+ | _ => Some (readError s : t))
+ (fn s =>
+ case s of
+ "" => Some None
+ | _ => case read s of
+ None => None
+ | v => Some v)
+
fun txt (t ::: Type) (ctx ::: {Unit}) (use ::: {Type}) (_ : show t) (v : t) =
cdata (show v)
diff --git a/lib/ur/top.urs b/lib/ur/top.urs
index 60b6dac2..4ed64075 100644
--- a/lib/ur/top.urs
+++ b/lib/ur/top.urs
@@ -39,6 +39,9 @@ val ex : tf :: (Type -> Type) -> choice :: Type -> tf choice -> ex tf
val compose : t1 ::: Type -> t2 ::: Type -> t3 ::: Type
-> (t2 -> t3) -> (t1 -> t2) -> (t1 -> t3)
+val show_option : t ::: Type -> show t -> show (option t)
+val read_option : t ::: Type -> read t -> read (option t)
+
val txt : t ::: Type -> ctx ::: {Unit} -> use ::: {Type} -> show t -> t
-> xml ctx use []