| 1 | (* Copyright (C) 1999-2005 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 Sum(S: SUM_STRUCTS): SUM = |
| 9 | struct |
| 10 | |
| 11 | open S |
| 12 | |
| 13 | datatype t = |
| 14 | X of X.t |
| 15 | | Y of Y.t |
| 16 | |
| 17 | val outX = |
| 18 | fn X x => x |
| 19 | | _ => Error.bug "Sum.outX" |
| 20 | |
| 21 | val outY = |
| 22 | fn Y y => y |
| 23 | | _ => Error.bug "Sum.outY" |
| 24 | |
| 25 | val map = |
| 26 | fn (X x, f, _) => f x |
| 27 | | (Y y, _, f) => f y |
| 28 | |
| 29 | val equals = |
| 30 | fn (X l, X l') => X.equals(l, l') |
| 31 | | (Y l, Y l') => Y.equals(l, l') |
| 32 | | _ => false |
| 33 | |
| 34 | fun layout s = map(s, X.layout, Y.layout) |
| 35 | |
| 36 | end |