Ur/Web: tests/foldm.ur annotate

Tutorial: up to First-Class Polymorphism

author	Adam Chlipala <adam@chlipala.net>
date	Sun, 17 Jul 2011 11:00:04 -0400
parents	71bafe66dbe1
children

rev	line source
adamc@75	1 con currier = fold (fn nm => fn t => fn acc => t -> acc) {}
adamc@75	2
adamc@75	3 signature S = sig
adamc@75	4 type t
adamc@75	5 val x : t
adamc@75	6
adamc@75	7 con rs :: {Type}
adamc@75	8 val create : currier rs -> t
adamc@75	9 end
adamc@75	10
adamc@75	11 functor Currier (M : sig con rs :: {Type} end) : S where con rs = M.rs = struct
adamc@75	12 val currier : rs :: {Type} -> currier rs =
adamc@75	13 fold [currier] (fn nm :: Name => fn t :: Type => fn rest :: {Type} => fn acc => fn x : t => acc) {}
adamc@75	14
adamc@75	15 type t = currier M.rs
adamc@75	16 val x = currier [M.rs]
adamc@75	17
adamc@75	18 con rs = M.rs
adamc@75	19 val create : t -> t = fn x => x
adamc@75	20 end
adamc@75	21
adamc@75	22 structure ChefsSpecial = Currier(struct
adamc@75	23 con rs = [A = int, B = float]
adamc@75	24 end)
adamc@75	25
adamc@75	26 val main = ChefsSpecial.x

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