# HG changeset patch
# User Edward Z. Yang <ezyang@mit.edu>
# Date 1343335717 14400
# Node ID f55f66c6fdeef109db6f195360ae7d182d6756f3
# Parent  ca1c07d49b5e6746036edcc6ff9c62b7d335abd9
Migrate ap method to Record module.

diff -r ca1c07d49b5e -r f55f66c6fdee lib.urp
--- a/lib.urp	Thu Jul 26 16:39:02 2012 -0400
+++ b/lib.urp	Thu Jul 26 16:48:37 2012 -0400
@@ -4,9 +4,9 @@
 incl
 mem
 eq
+record
 variant
 json
-record
 sql
 parse
 html
diff -r ca1c07d49b5e -r f55f66c6fdee record.ur
--- a/record.ur	Thu Jul 26 16:39:02 2012 -0400
+++ b/record.ur	Thu Jul 26 16:48:37 2012 -0400
@@ -12,3 +12,7 @@
      (fn [nm ::_] [t ::_] [r ::_] [[nm] ~ r] isEq x y acc =>
          acc && @eq isEq x y)
      True fl eqs r1 r2
+
+fun ap [K] [tf1 :: K -> Type] [tf2 :: K -> Type]
+       [r ::: {K}] (fl : folder r) (fs : $(map (fn t => tf1 t -> tf2 t) r)) (xs : $(map tf1 r))
+  = @map2 [fn t => tf1 t -> tf2 t] [fn t => tf1 t] [tf2] (fn [t] f x => f x) fl fs xs
diff -r ca1c07d49b5e -r f55f66c6fdee record.urs
--- a/record.urs	Thu Jul 26 16:39:02 2012 -0400
+++ b/record.urs	Thu Jul 26 16:48:37 2012 -0400
@@ -5,3 +5,10 @@
 
 val equal : ts ::: {Type} -> $(map eq ts) -> folder ts -> $ts -> $ts -> bool
 (* Are two records equal? *)
+
+(* Analogous to applicative ap e.g. <*>, of type [f (a -> b) -> f a -> f b] *)
+val ap : K --> tf1 :: (K -> Type) -> tf2 :: (K -> Type)
+         -> r ::: {K} -> folder r
+         -> $(map (fn t => tf1 t -> tf2 t) r)
+         -> $(map tf1 r)
+         -> $(map tf2 r)
diff -r ca1c07d49b5e -r f55f66c6fdee variant.ur
--- a/variant.ur	Thu Jul 26 16:39:02 2012 -0400
+++ b/variant.ur	Thu Jul 26 16:48:37 2012 -0400
@@ -142,4 +142,4 @@
 fun declareCase [ts] [t] [a] (f : (a -> variant ts) -> a -> t) : type_case ts t a = f
 fun typeCase [ts] [t] (v : variant ts) (dstrs : $(map (type_case ts t) ts)) (fl : folder ts) : t
 (* Ur/Web not clever enough to calculate these folders, it seems *)
-  = match v (@ap [fn a => a -> variant ts] [fn a => a -> t] fl dstrs (@mkLabels fl))
+  = match v (@Record.ap [fn a => a -> variant ts] [fn a => a -> t] fl dstrs (@mkLabels fl))