diff options
Diffstat (limited to 'src/triple_key_fn.sml')
| -rw-r--r-- | src/triple_key_fn.sml | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/src/triple_key_fn.sml b/src/triple_key_fn.sml new file mode 100644 index 00000000..ba77c60b --- /dev/null +++ b/src/triple_key_fn.sml @@ -0,0 +1,15 @@ +functor TripleKeyFn (structure I : ORD_KEY + structure J : ORD_KEY + structure K : ORD_KEY) + : ORD_KEY where type ord_key = I.ord_key * J.ord_key * K.ord_key = struct + +type ord_key = I.ord_key * J.ord_key * K.ord_key + +fun compare ((i1, j1, k1), (i2, j2, k2)) = + case I.compare (i1, i2) of + EQUAL => (case J.compare (j1, j2) of + EQUAL => K.compare (k1, k2) + | ord => ord) + | ord => ord + +end |