[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 7 commits: users-guide: Rename 8.12 to 9.0
Marge Bot
gitlab at gitlab.haskell.org
Thu Aug 6 23:24:27 UTC 2020
Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC
Commits:
c456bab3 by Takenobu Tani at 2020-08-06T18:51:14+09:00
users-guide: Rename 8.12 to 9.0
GHC 8.12.1 has been renamed to GHC 9.0.1.
See also:
https://mail.haskell.org/pipermail/ghc-devs/2020-July/019083.html
[skip ci]
- - - - -
2aacccb9 by Vladislav Zavialov at 2020-08-06T19:24:23-04:00
Grammar for types and data/newtype constructors
Before this patch, we parsed types into a reversed sequence
of operators and operands. For example, (F x y + G a b * X)
would be parsed as [X, *, b, a, G, +, y, x, F],
using a simple grammar:
tyapps
: tyapp
| tyapps tyapp
tyapp
: atype
| PREFIX_AT atype
| tyop
| unpackedness
Then we used a hand-written state machine to assemble this
either into a type, using 'mergeOps',
or into a constructor, using 'mergeDataCon'.
This is due to a syntactic ambiguity:
data T1 a = MkT1 a
data T2 a = Ord a => MkT2 a
In T1, what follows after the = sign is a data/newtype constructor
declaration. However, in T2, what follows is a type (of kind
Constraint). We don't know which of the two we are parsing until we
encounter =>, and we cannot check for => without unlimited lookahead.
This poses a few issues when it comes to e.g. infix operators:
data I1 = Int :+ Bool :+ Char -- bad
data I2 = Int :+ Bool :+ Char => MkI2 -- fine
By this issue alone we are forced into parsing into an intermediate
representation and doing a separate validation pass.
However, should that intermediate representation be as low-level as a
flat sequence of operators and operands?
Before GHC Proposal #229, the answer was Yes, due to some particularly
nasty corner cases:
data T = ! A :+ ! B -- used to be fine, hard to parse
data T = ! A :+ ! B => MkT -- bad
However, now the answer is No, as this corner case is gone:
data T = ! A :+ ! B -- bad
data T = ! A :+ ! B => MkT -- bad
This means we can write a proper grammar for types, overloading it in
the DisambECP style, see Note [Ambiguous syntactic categories].
With this patch, we introduce a new class, DisambTD. Just like
DisambECP is used to disambiguate between expressions, commands, and patterns,
DisambTD is used to disambiguate between types and data/newtype constructors.
This way, we get a proper, declarative grammar for constructors and
types:
infixtype
: ftype
| ftype tyop infixtype
| unpackedness infixtype
ftype
: atype
| tyop
| ftype tyarg
| ftype PREFIX_AT tyarg
tyarg
: atype
| unpackedness atype
And having a grammar for types means we are a step closer to using a
single grammar for types and expressions.
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183de579 by Vladislav Zavialov at 2020-08-06T19:24:23-04:00
Clean up the story around runPV/runECP_P/runECP_PV
This patch started as a small documentation change, an attempt to make
Note [Parser-Validator] and Note [Ambiguous syntactic categories]
more clear and up-to-date.
But it turned out that runECP_P/runECP_PV are weakly motivated,
and it's easier to remove them than to find a good rationale/explanation
for their existence.
As the result, there's a bit of refactoring in addition to
a documentation update.
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b54e8a5a by Vladislav Zavialov at 2020-08-06T19:24:23-04:00
Fix debug_ppr_ty ForAllTy (#18522)
Before this change, GHC would
pretty-print forall k. forall a -> ()
as forall @k a. ()
which isn't even valid Haskell.
- - - - -
b221579f by Vladislav Zavialov at 2020-08-06T19:24:23-04:00
Fix visible forall in ppr_ty (#18522)
Before this patch, this type:
T :: forall k -> (k ~ k) => forall j -> k -> j -> Type
was printed incorrectly as:
T :: forall k j -> (k ~ k) => k -> j -> Type
- - - - -
e855d06e by Richard Eisenberg at 2020-08-06T19:24:24-04:00
Fail eagerly on a lev-poly datacon arg
Close #18534.
See commentary in the patch.
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1aff3f96 by Sylvain Henry at 2020-08-06T19:24:25-04:00
Use a type alias for Ways
- - - - -
30 changed files:
- compiler/GHC/Core/TyCo/Ppr.hs
- compiler/GHC/Driver/Session.hs
- compiler/GHC/Iface/Type.hs
- compiler/GHC/Parser.y
- compiler/GHC/Parser/PostProcess.hs
- compiler/GHC/Platform/Profile.hs
- compiler/GHC/Platform/Ways.hs
- compiler/GHC/Tc/TyCl.hs
- compiler/GHC/Unit/State.hs
- docs/users_guide/8.12.1-notes.rst → docs/users_guide/9.0.1-notes.rst
- docs/users_guide/exts/lambda_case.rst
- docs/users_guide/exts/lexical_negation.rst
- docs/users_guide/exts/linear_types.rst
- docs/users_guide/exts/negative_literals.rst
- docs/users_guide/exts/qualified_do.rst
- docs/users_guide/release-notes.rst
- docs/users_guide/using-warnings.rst
- + testsuite/tests/ghc-api/T18522-dbg-ppr.hs
- + testsuite/tests/ghc-api/T18522-dbg-ppr.stdout
- testsuite/tests/ghc-api/all.T
- testsuite/tests/parser/should_fail/T12045d.stderr
- testsuite/tests/parser/should_fail/strictnessDataCon_B.stderr
- testsuite/tests/parser/should_fail/typeops_A.stderr
- testsuite/tests/parser/should_fail/typeops_C.stderr
- testsuite/tests/parser/should_fail/unpack_empty_type.stderr
- testsuite/tests/parser/should_fail/unpack_inside_type.stderr
- + testsuite/tests/polykinds/T18522-ppr.script
- + testsuite/tests/polykinds/T18522-ppr.stdout
- testsuite/tests/polykinds/all.T
- + testsuite/tests/typecheck/should_fail/T18534.hs
The diff was not included because it is too large.
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/63348155404c64334fa864454132630f9d2a4d7f...1aff3f9692f4a0c7754ca00aa0ff07ba8659b1c3
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/63348155404c64334fa864454132630f9d2a4d7f...1aff3f9692f4a0c7754ca00aa0ff07ba8659b1c3
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