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<h3>
Simon Peyton Jones pushed to branch wip/T17173
at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
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<h4>
Commits:
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<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/e1fb31571f4eb16ea6fe2803a088d15bcbc5f0c4">e1fb3157</a></strong>
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<span>by Simon Peyton Jones</span>
<i>at 2020-04-17T16:55:46+01:00</i>
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<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">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.
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<a href="#cc97d81e7223ad4a3a5e801156ca632f9fa75654">
compiler/GHC/Hs/Expr.hs
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<a href="#7a1af22e4c32b9aa6ec708d9d3788e1c4db5da9a">
compiler/GHC/Hs/Utils.hs
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<a href="#6bdd5abc649727f2a802bc96ce5c276de19d3726">
compiler/GHC/HsToCore/Expr.hs
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<a href="#16b273b96a1c03d4261e2ac6de4cc456ba2dd014">
compiler/GHC/Rename/Splice.hs
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compiler/GHC/Tc/Gen/Arrow.hs
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compiler/GHC/Tc/Gen/Bind.hs
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compiler/GHC/Tc/Gen/Expr.hs
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<a href="#8dec347fbe40358b852d7b50ace1e4d62b9b6660">
compiler/GHC/Tc/Gen/Expr.hs-boot
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compiler/GHC/Tc/Gen/Foreign.hs
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compiler/GHC/Tc/Gen/HsType.hs
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compiler/GHC/Tc/Gen/Match.hs
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compiler/GHC/Tc/Gen/Pat.hs
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compiler/GHC/Tc/Gen/Rule.hs
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compiler/GHC/Tc/Gen/Splice.hs
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compiler/GHC/Tc/Module.hs
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compiler/GHC/Tc/TyCl/PatSyn.hs
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compiler/GHC/Tc/Types/Origin.hs
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compiler/GHC/Tc/Utils/Instantiate.hs
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compiler/GHC/Tc/Utils/Monad.hs
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compiler/GHC/Tc/Utils/TcMType.hs
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compiler/GHC/Tc/Utils/TcType.hs
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compiler/GHC/Tc/Utils/Unify.hs
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compiler/GHC/Tc/Utils/Zonk.hs
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libraries/base/tests/T9681.stderr
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testsuite/tests/ado/T13242a.stderr
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testsuite/tests/ado/ado002.stderr
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testsuite/tests/annotations/should_fail/annfail08.stderr
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testsuite/tests/driver/T2182.stderr
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