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Diffstat (limited to 'kernel/univ.ml')
| -rw-r--r-- | kernel/univ.ml | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/univ.ml b/kernel/univ.ml index fbb047364..c42b66749 100644 --- a/kernel/univ.ml +++ b/kernel/univ.ml @@ -759,6 +759,13 @@ struct | Invariant, _ | _, Invariant -> Invariant | Covariant, Covariant -> Covariant + let check_subtype x y = match x, y with + | (Irrelevant | Covariant | Invariant), Irrelevant -> true + | Irrelevant, Covariant -> false + | (Covariant | Invariant), Covariant -> true + | (Irrelevant | Covariant), Invariant -> false + | Invariant, Invariant -> true + let pr = function | Irrelevant -> str "*" | Covariant -> str "+" |