diff options
| 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 /testsuite/tests/gadt | |
| 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 'testsuite/tests/gadt')
| -rw-r--r-- | testsuite/tests/gadt/gadt13.stderr | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/testsuite/tests/gadt/gadt13.stderr b/testsuite/tests/gadt/gadt13.stderr index 6673ff68b0..cea221944b 100644 --- a/testsuite/tests/gadt/gadt13.stderr +++ b/testsuite/tests/gadt/gadt13.stderr @@ -8,10 +8,10 @@ gadt13.hs:15:13: error: in an equation for ‘shw’ at gadt13.hs:15:6-8 ‘p’ is a rigid type variable bound by - the inferred type of shw :: Term a -> p at gadt13.hs:15:1-30 + the inferred type of shw :: Term a -> p + at gadt13.hs:15:1-30 Possible fix: add a type signature for ‘shw’ - • Possible cause: ‘(.)’ is applied to too many arguments - In the expression: ("I " ++) . shows t + • In the expression: ("I " ++) . shows t In an equation for ‘shw’: shw (I t) = ("I " ++) . shows t • Relevant bindings include shw :: Term a -> p (bound at gadt13.hs:15:1) |