Mercurial > urweb
view tests/foldm.ur @ 1886:b7cd3c7c7edd
Interpret 'table' signature items more flexibly, automatically adding (Ur) constraints to support a kind of subtyping over (SQL) constraint sets
author | Adam Chlipala <adam@chlipala.net> |
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date | Mon, 04 Nov 2013 15:14:23 -0500 |
parents | 71bafe66dbe1 |
children |
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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