From 35fba70509d9fb219b2a88f8e7bd246b2671b39b Mon Sep 17 00:00:00 2001
From: Gaëtan Gilbert
Date: Thu, 9 Nov 2017 17:27:58 +0100
Subject: 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 |=  *)
---
 interp/discharge.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'interp')

diff --git a/interp/discharge.ml b/interp/discharge.ml
index 75bfca3078..710f88c3ff 100644
--- a/interp/discharge.ml
+++ b/interp/discharge.ml
@@ -92,7 +92,7 @@ let process_inductive info modlist mib =
       let auctx = Univ.ACumulativityInfo.univ_context cumi in
       let subst, auctx = Lib.discharge_abstract_universe_context info auctx in
       let auctx = Univ.AUContext.repr auctx in
-      subst, Cumulative_ind_entry (Universes.univ_inf_ind_from_universe_context auctx)
+      subst, Cumulative_ind_entry (Univ.CumulativityInfo.from_universe_context auctx)
   in
   let discharge c = Vars.subst_univs_level_constr subst (expmod_constr modlist c) in
   let inds =
-- 
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