[Git][ghc/ghc][master] Do eager instantation in terms

[Marge Bot]

 Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
ffde2348 by Simon Peyton Jones at 2020-04-22T23:13:06-04:00
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.

- - - - -


30 changed files:

- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/Utils.hs
- compiler/GHC/HsToCore/Expr.hs
- compiler/GHC/Rename/Splice.hs
- compiler/GHC/Tc/Gen/Arrow.hs
- compiler/GHC/Tc/Gen/Bind.hs
- compiler/GHC/Tc/Gen/Expr.hs
- compiler/GHC/Tc/Gen/Expr.hs-boot
- compiler/GHC/Tc/Gen/Foreign.hs
- compiler/GHC/Tc/Gen/HsType.hs
- compiler/GHC/Tc/Gen/Match.hs
- compiler/GHC/Tc/Gen/Pat.hs
- compiler/GHC/Tc/Gen/Rule.hs
- compiler/GHC/Tc/Gen/Splice.hs
- compiler/GHC/Tc/Module.hs
- compiler/GHC/Tc/TyCl/PatSyn.hs
- compiler/GHC/Tc/Types/Origin.hs
- compiler/GHC/Tc/Utils/Instantiate.hs
- compiler/GHC/Tc/Utils/Monad.hs
- compiler/GHC/Tc/Utils/TcMType.hs
- compiler/GHC/Tc/Utils/TcType.hs
- compiler/GHC/Tc/Utils/Unify.hs
- compiler/GHC/Tc/Utils/Zonk.hs
- docs/users_guide/8.12.1-notes.rst
- libraries/base/tests/T9681.stderr
- testsuite/tests/ado/T13242a.stderr
- testsuite/tests/ado/ado002.stderr
- testsuite/tests/annotations/should_fail/annfail08.stderr
- testsuite/tests/driver/T2182.stderr
- testsuite/tests/gadt/gadt13.stderr


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/ffde234854f49dba9ec4735aad74b30fd2deee29

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/ffde234854f49dba9ec4735aad74b30fd2deee29
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