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| author |  Gaëtan Gilbert <gaetan.gilbert@skyskimmer.net> | 2017-11-09 17:27:58 +0100 |
|---|---|---|
| committer | Gaëtan Gilbert <gaetan.gilbert@skyskimmer.net> | 2018-02-10 01:34:19 +0100 |
| commit | 35fba70509d9fb219b2a88f8e7bd246b2671b39b (patch) | |
| tree | 21cdb9aa905ef8f6375aa6cd119254794233d0ac /kernel/reduction.mli | |
| parent | 10d3d803e6b57024dd15df7d61670ce42260948a (diff) | |
Simplification: cumulativity information is variance information.
Since cumulativity of an inductive type is the universe constraints
which make a term convertible with its universe-renamed copy, the only
constraints we can get are between a universe and its copy.
As such we do not need to be able to represent arbitrary constraints
between universes and copied universes in a double-sized ucontext,
instead we can just keep around an array describing whether a bound
universe is covariant, invariant or irrelevant (CIC has no
contravariant conversion rule).
Printing is fairly obtuse and should be improved: when we print the
CumulativityInfo we add marks to the universes of the instance: = for
invariant, + for covariant and * for irrelevant. ie
Record Foo@{i j k} := { foo : Type@{i} -> Type@{j} }.
Print Foo.
gives
Cumulative Record Foo : Type@{max(i+1, j+1)} := Build_Foo
{ foo : Type@{i} -> Type@{j} }
(* =i +j *k |= *)
Diffstat (limited to 'kernel/reduction.mli')
| -rw-r--r-- | kernel/reduction.mli | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/reduction.mli b/kernel/reduction.mli index 059f259ae..d064b3687 100644 --- a/kernel/reduction.mli +++ b/kernel/reduction.mli @@ -47,6 +47,9 @@ type ('a,'b) generic_conversion_function = env -> 'b universe_state -> 'a -> 'a type 'a infer_conversion_function = env -> UGraph.t -> 'a -> 'a -> Univ.Constraint.t +val get_cumulativity_constraints : conv_pb -> Univ.ACumulativityInfo.t -> + Univ.Instance.t -> Univ.Instance.t -> Univ.Constraint.t + val sort_cmp_universes : env -> conv_pb -> Sorts.t -> Sorts.t -> 'a * 'a universe_compare -> 'a * 'a universe_compare |