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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2020-04-08 23:08:12 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2020-04-22 23:13:06 -0400 |
| commit | ffde234854f49dba9ec4735aad74b30fd2deee29 (patch) | |
| tree | 80409f70e0de9164441d1cf860b386df4318e5c3 /compiler/GHC/Tc/TyCl/PatSyn.hs | |
| parent | 34a45ee600d5346f5d1728047fa185698ed7ee84 (diff) | |
| download | haskell-ffde234854f49dba9ec4735aad74b30fd2deee29.tar.gz | |
Do eager instantation in terms
This patch implements eager instantiation, a small but critical change
to the type inference engine, #17173. The main change is this:
When inferring types, always return an instantiated type
(for now, deeply instantiated; in future shallowly instantiated)
There is more discussion in
https://www.tweag.io/posts/2020-04-02-lazy-eager-instantiation.html
There is quite a bit of refactoring in this patch:
* The ir_inst field of GHC.Tc.Utils.TcType.InferResultk
has entirely gone. So tcInferInst and tcInferNoInst have collapsed
into tcInfer.
* Type inference of applications, via tcInferApp and
tcInferAppHead, are substantially refactored, preparing
the way for Quick Look impredicativity.
* New pure function GHC.Tc.Gen.Expr.collectHsArgs and applyHsArgs
are beatifully dual. We can see the zipper!
* GHC.Tc.Gen.Expr.tcArgs is now much nicer; no longer needs to return
a wrapper
* In HsExpr, HsTypeApp now contains the the actual type argument,
and is used in desugaring, rather than putting it in a mysterious
wrapper.
* I struggled a bit with good error reporting in
Unify.matchActualFunTysPart. It's a little bit simpler than before,
but still not great.
Some smaller things
* Rename tcPolyExpr --> tcCheckExpr
tcMonoExpr --> tcLExpr
* tcPatSig moves from GHC.Tc.Gen.HsType to GHC.Tc.Gen.Pat
Metric Decrease:
T9961
Reduction of 1.6% in comiler allocation on T9961, I think.
Diffstat (limited to 'compiler/GHC/Tc/TyCl/PatSyn.hs')
| -rw-r--r-- | compiler/GHC/Tc/TyCl/PatSyn.hs | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/compiler/GHC/Tc/TyCl/PatSyn.hs b/compiler/GHC/Tc/TyCl/PatSyn.hs index 0a719d90d2..797ff2f594 100644 --- a/compiler/GHC/Tc/TyCl/PatSyn.hs +++ b/compiler/GHC/Tc/TyCl/PatSyn.hs @@ -147,8 +147,7 @@ tcInferPatSynDecl (PSB { psb_id = lname@(L _ name), psb_args = details ; let (arg_names, rec_fields, is_infix) = collectPatSynArgInfo details ; (tclvl, wanted, ((lpat', args), pat_ty)) <- pushLevelAndCaptureConstraints $ - tcInferNoInst $ \ exp_ty -> - tcPat PatSyn lpat exp_ty $ + tcInferPat PatSyn lpat $ mapM tcLookupId arg_names ; let (ex_tvs, prov_dicts) = tcCollectEx lpat' @@ -386,9 +385,9 @@ tcCheckPatSynDecl psb@PSB{ psb_id = lname@(L _ name), psb_args = details ; req_dicts <- newEvVars req_theta ; (tclvl, wanted, (lpat', (ex_tvs', prov_dicts, args'))) <- ASSERT2( equalLength arg_names arg_tys, ppr name $$ ppr arg_names $$ ppr arg_tys ) - pushLevelAndCaptureConstraints $ - tcExtendTyVarEnv univ_tvs $ - tcPat PatSyn lpat (mkCheckExpType pat_ty) $ + pushLevelAndCaptureConstraints $ + tcExtendTyVarEnv univ_tvs $ + tcCheckPat PatSyn lpat pat_ty $ do { let in_scope = mkInScopeSet (mkVarSet univ_tvs) empty_subst = mkEmptyTCvSubst in_scope ; (subst, ex_tvs') <- mapAccumLM newMetaTyVarX empty_subst ex_tvs |