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7f918cf1 CE |
1 | (* Copyright (C) 1999-2006 Henry Cejtin, Matthew Fluet, Suresh |
2 | * Jagannathan, and Stephen Weeks. | |
3 | * | |
4 | * MLton is released under a BSD-style license. | |
5 | * See the file MLton-LICENSE for details. | |
6 | *) | |
7 | ||
8 | functor Ring(S: RING_STRUCTS):> RING where type t = S.t = | |
9 | struct | |
10 | ||
11 | open S | |
12 | ||
13 | fun a - b = a + (~ b) | |
14 | ||
15 | fun isZero a = equals(a, zero) | |
16 | ||
17 | fun double n = n + n | |
18 | ||
19 | fun square n = n * n | |
20 | ||
21 | fun sum l = List.fold(l, zero, op +) | |
22 | ||
23 | end |