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comparison tests/type_classMod2.lac @ 218:a3413288cce1

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Signature ascription for type classes
author Adam Chlipala <adamc@hcoop.net>
date Sat, 16 Aug 2008 16:57:21 -0400
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217:56db662ebcfd 218:a3413288cce1
1 signature S = sig
2 class c
3 val default : t :: Type -> c t -> t
4
5 val string_c : c string
6 val int_c : c int
7 end
8
9 structure M : S = struct
10 class c t = t
11 val default = fn t :: Type => fn v : c t => v
12
13 val int_c : c int = 0
14 val string_c : c string = "Hi"
15 end
16
17 val hi = M.default [string] _
18 val zero = M.default [int] _