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| author | Simon Peyton Jones <simon.peytonjones@gmail.com> | 2023-03-31 11:28:54 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2023-05-12 23:50:25 -0400 |
| commit | 8b9b7dbc913b66795c283683c7fe1fb48672666d (patch) | |
| tree | 920a6f25019a433283e3fcb17c7edd984d283443 /compiler/GHC/Tc/Utils/Unify.hs-boot | |
| parent | dc0c957439c2fae14547de24ff665fc4f5db56a7 (diff) | |
| download | haskell-8b9b7dbc913b66795c283683c7fe1fb48672666d.tar.gz | |
Use the eager unifier in the constraint solver
This patch continues the refactoring of the constraint solver
described in #23070.
The Big Deal in this patch is to call the regular, eager unifier from the
constraint solver, when we want to create new equalities. This
replaces the existing, unifyWanted which amounted to
yet-another-unifier, so it reduces duplication of a rather subtle
piece of technology. See
* Note [The eager unifier] in GHC.Tc.Utils.Unify
* GHC.Tc.Solver.Monad.wrapUnifierTcS
I did lots of other refactoring along the way
* I simplified the treatment of right hand sides that contain CoercionHoles.
Now, a constraint that contains a hetero-kind CoercionHole is non-canonical,
and cannot be used for rewriting or unification alike. This required me
to add the ch_hertero_kind flag to CoercionHole, with consequent knock-on
effects. See wrinkle (2) of `Note [Equalities with incompatible kinds]` in
GHC.Tc.Solver.Equality.
* I refactored the StopOrContinue type to add StartAgain, so that after a
fundep improvement (for example) we can simply start the pipeline again.
* I got rid of the unpleasant (and inefficient) rewriterSetFromType/Co functions.
With Richard I concluded that they are never needed.
* I discovered Wrinkle (W1) in Note [Wanteds rewrite Wanteds] in
GHC.Tc.Types.Constraint, and therefore now prioritise non-rewritten equalities.
Quite a few error messages change, I think always for the better.
Compiler runtime stays about the same, with one outlier: a 17% improvement in T17836
Metric Decrease:
T17836
T18223
Diffstat (limited to 'compiler/GHC/Tc/Utils/Unify.hs-boot')
| -rw-r--r-- | compiler/GHC/Tc/Utils/Unify.hs-boot | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/compiler/GHC/Tc/Utils/Unify.hs-boot b/compiler/GHC/Tc/Utils/Unify.hs-boot index 0d82ea613e..9b75cea113 100644 --- a/compiler/GHC/Tc/Utils/Unify.hs-boot +++ b/compiler/GHC/Tc/Utils/Unify.hs-boot @@ -9,8 +9,9 @@ import GHC.Tc.Types.Origin ( CtOrigin, TypedThing ) -- This boot file exists only to tie the knot between --- GHC.Tc.Utils.Unify and GHC.Tc.Utils.Instantiate +-- GHC.Tc.Utils.Unify and GHC.Tc.Utils.Instantiate/GHC.Tc.Utils.TcMType -unifyType :: Maybe TypedThing -> TcTauType -> TcTauType -> TcM TcCoercion +unifyType :: Maybe TypedThing -> TcTauType -> TcTauType -> TcM TcCoercion +unifyInvisibleType :: TcTauType -> TcTauType -> TcM TcCoercion tcSubMult :: CtOrigin -> Mult -> Mult -> TcM HsWrapper |