Mercurial > urweb
diff tests/foldm.lac @ 75:88ffb3d61817
Folding through a functor
author | Adam Chlipala <adamc@hcoop.net> |
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date | Thu, 26 Jun 2008 12:35:26 -0400 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/tests/foldm.lac Thu Jun 26 12:35:26 2008 -0400 @@ -0,0 +1,26 @@ +con currier = fold (fn nm => fn t => fn acc => t -> acc) {} + +signature S = sig + type t + val x : t + + con rs :: {Type} + val create : currier rs -> t +end + +functor Currier (M : sig con rs :: {Type} end) : S where con rs = M.rs = struct + val currier : rs :: {Type} -> currier rs = + fold [currier] (fn nm :: Name => fn t :: Type => fn rest :: {Type} => fn acc => fn x : t => acc) {} + + type t = currier M.rs + val x = currier [M.rs] + + con rs = M.rs + val create : t -> t = fn x => x +end + +structure ChefsSpecial = Currier(struct + con rs = [A = int, B = float] +end) + +val main = ChefsSpecial.x