diff options
| 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 /checker/reduction.ml | |
| 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 'checker/reduction.ml')
| -rw-r--r-- | checker/reduction.ml | 17 |
1 files changed, 5 insertions, 12 deletions
diff --git a/checker/reduction.ml b/checker/reduction.ml index 29bb8901e..2297c90b3 100644 --- a/checker/reduction.ml +++ b/checker/reduction.ml @@ -158,24 +158,17 @@ let compare_stacks f fmind lft1 stk1 lft2 stk2 = let convert_inductive_instances cv_pb cumi u u' univs = let len_instance = Univ.AUContext.size (Univ.ACumulativityInfo.univ_context cumi) in - let ind_subtypctx = Univ.ACumulativityInfo.subtyp_context cumi in if not ((len_instance = Univ.Instance.length u) && (len_instance = Univ.Instance.length u')) then anomaly (Pp.str "Invalid inductive subtyping encountered!") else - let comp_cst = - let comp_subst = (Univ.Instance.append u u') in - Univ.AUContext.instantiate comp_subst ind_subtypctx - in + let variance = Univ.ACumulativityInfo.variance cumi in let comp_cst = match cv_pb with - CONV -> - let comp_cst' = - let comp_subst = (Univ.Instance.append u' u) in - Univ.AUContext.instantiate comp_subst ind_subtypctx - in - Univ.Constraint.union comp_cst comp_cst' - | CUMUL -> comp_cst + | CONV -> + Univ.Variance.eq_constraints variance u u' Univ.Constraint.empty + | CUMUL -> + Univ.Variance.leq_constraints variance u u' Univ.Constraint.empty in if (Univ.check_constraints comp_cst univs) then () else raise NotConvertible |