From: Siraaj Khandkar <siraaj@khandkar.net>
Date: Wed, 29 Apr 2015 00:00:55 +0000 (-0400)
Subject: Implement automatic currying.
X-Git-Tag: 3.1.0^0
X-Git-Url: https://git.xandkar.net/?a=commitdiff_plain;h=e033aadea66cc7f68e3a66cde23a2edfe4c4e9e6;p=hope.git

Implement automatic currying.
---

diff --git a/src/hope.app.src b/src/hope.app.src
index 9d0ece1..f04e3ae 100644
--- a/src/hope.app.src
+++ b/src/hope.app.src
@@ -1,7 +1,7 @@
 {application, hope,
  [
   {description, "Higher Order Programming in Erlang"},
-  {vsn, "3.0.0"},
+  {vsn, "3.1.0"},
   {registered, []},
   {applications, [
                   kernel,
diff --git a/src/hope_fun.erl b/src/hope_fun.erl
index 61babe9..5ee6730 100644
--- a/src/hope_fun.erl
+++ b/src/hope_fun.erl
@@ -2,9 +2,23 @@
 
 -export(
     [ id/1
+    , curry/1
     ]).
 
 -spec id(A) ->
     A.
 id(X) ->
     X.
+
+-spec curry(fun()) ->
+    fun().
+curry(F) ->
+    {value, {arity, Arity}} = lists:keysearch(arity, 1, erlang:fun_info(F)),
+    curry(F, [], Arity).
+
+-spec curry(fun(), list(), integer()) ->
+    fun().
+curry(F, Args, 0) ->
+    apply(F, lists:reverse(Args));
+curry(F, Args, Arity) ->
+    fun (X) -> curry(F, [X | Args], Arity - 1) end.
diff --git a/test/hope_fun_SUITE.erl b/test/hope_fun_SUITE.erl
index d4e2281..910cc49 100644
--- a/test/hope_fun_SUITE.erl
+++ b/test/hope_fun_SUITE.erl
@@ -9,6 +9,7 @@
 %% Test cases
 -export(
     [ t_id/1
+    , t_curry/1
     ]).
 
 
@@ -26,6 +27,7 @@ all() ->
 groups() ->
     Tests =
         [ t_id
+        , t_curry
         ],
     Properties = [parallel],
     [ {?GROUP, Properties, Tests}
@@ -39,3 +41,20 @@ groups() ->
 t_id(_Cfg) ->
     X = foo,
     X = hope_fun:id(X).
+
+t_curry(_Cfg) ->
+    Single = fun (X) -> X end,
+    Double = fun (X, Y) -> {X, Y} end,
+    Triple = fun (X, Y, Z) -> {X, Y, Z} end,
+
+    F = hope_fun:curry(Single),
+    a = F(a),
+
+    G1 = hope_fun:curry(Double),
+    G = G1(a),
+    {a, b} = G(b),
+
+    H1 = hope_fun:curry(Triple),
+    H2 = H1(a),
+    H  = H2(b),
+    {a, b, c} = H(c).