[commit: ghc] master: Implement pattern synonyms (4f8369b)
git at git.haskell.org
git at git.haskell.org
Mon Jan 20 20:58:23 UTC 2014
Repository : ssh://git@git.haskell.org/ghc
On branch : master
Link : http://ghc.haskell.org/trac/ghc/changeset/4f8369bf47d27b11415db251e816ef1a2e1eb3d8/ghc
>---------------------------------------------------------------
commit 4f8369bf47d27b11415db251e816ef1a2e1eb3d8
Author: Dr. ERDI Gergo <gergo at erdi.hu>
Date: Mon Jan 13 20:12:34 2014 +0800
Implement pattern synonyms
This patch implements Pattern Synonyms (enabled by -XPatternSynonyms),
allowing y ou to assign names to a pattern and abstract over it.
The rundown is this:
* Named patterns are introduced by the new 'pattern' keyword, and can
be either *unidirectional* or *bidirectional*. A unidirectional
pattern is, in the simplest sense, simply an 'alias' for a pattern,
where the LHS may mention variables to occur in the RHS. A
bidirectional pattern synonym occurs when a pattern may also be used
in expression context.
* Unidirectional patterns are declared like thus:
pattern P x <- x:_
The synonym 'P' may only occur in a pattern context:
foo :: [Int] -> Maybe Int
foo (P x) = Just x
foo _ = Nothing
* Bidirectional patterns are declared like thus:
pattern P x y = [x, y]
Here, P may not only occur as a pattern, but also as an expression
when given values for 'x' and 'y', i.e.
bar :: Int -> [Int]
bar x = P x 10
* Patterns can't yet have their own type signatures; signatures are inferred.
* Pattern synonyms may not be recursive, c.f. type synonyms.
* Pattern synonyms are also exported/imported using the 'pattern'
keyword in an import/export decl, i.e.
module Foo (pattern Bar) where ...
Note that pattern synonyms share the namespace of constructors, so
this disambiguation is required as a there may also be a 'Bar'
type in scope as well as the 'Bar' pattern.
* The semantics of a pattern synonym differ slightly from a typical
pattern: when using a synonym, the pattern itself is matched,
followed by all the arguments. This means that the strictness
differs slightly:
pattern P x y <- [x, y]
f (P True True) = True
f _ = False
g [True, True] = True
g _ = False
In the example, while `g (False:undefined)` evaluates to False,
`f (False:undefined)` results in undefined as both `x` and `y`
arguments are matched to `True`.
For more information, see the wiki:
https://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms
https://ghc.haskell.org/trac/ghc/wiki/PatternSynonyms/Implementation
Reviewed-by: Simon Peyton Jones <simonpj at microsoft.com>
Signed-off-by: Austin Seipp <austin at well-typed.com>
>---------------------------------------------------------------
4f8369bf47d27b11415db251e816ef1a2e1eb3d8
compiler/basicTypes/BasicTypes.lhs | 20 ++
compiler/basicTypes/ConLike.lhs | 82 +++++
compiler/basicTypes/DataCon.lhs-boot | 9 +-
compiler/basicTypes/OccName.lhs | 5 +-
compiler/basicTypes/PatSyn.lhs | 225 ++++++++++++++
compiler/basicTypes/PatSyn.lhs-boot | 19 ++
compiler/deSugar/Check.lhs | 52 +++-
compiler/deSugar/Coverage.lhs | 9 +-
compiler/deSugar/Desugar.lhs | 17 +-
compiler/deSugar/DsBinds.lhs | 12 +-
compiler/deSugar/DsExpr.lhs | 13 +-
compiler/deSugar/DsMeta.hs | 4 +-
compiler/deSugar/DsMonad.lhs | 18 +-
compiler/deSugar/DsUtils.lhs | 236 ++++++++------
compiler/deSugar/Match.lhs | 28 +-
compiler/deSugar/MatchCon.lhs | 59 +++-
compiler/ghc.cabal.in | 3 +
compiler/ghc.mk | 2 +
compiler/hsSyn/Convert.lhs | 8 +-
compiler/hsSyn/HsBinds.lhs | 100 +++++-
compiler/hsSyn/HsExpr.lhs | 4 +
compiler/hsSyn/HsPat.lhs | 22 +-
compiler/hsSyn/HsPat.lhs-boot | 2 +
compiler/hsSyn/HsTypes.lhs | 12 +-
compiler/hsSyn/HsUtils.lhs | 28 +-
compiler/iface/BinIface.hs | 3 +-
compiler/iface/BuildTyCl.lhs | 69 +++++
compiler/iface/IfaceSyn.lhs | 72 ++++-
compiler/iface/MkIface.lhs | 30 +-
compiler/iface/TcIface.lhs | 48 ++-
compiler/main/DynFlags.hs | 4 +-
compiler/main/HscMain.hs | 1 +
compiler/main/HscStats.hs | 63 ++--
compiler/main/HscTypes.lhs | 58 +++-
compiler/main/PprTyThing.hs | 29 +-
compiler/main/TidyPgm.lhs | 11 +-
compiler/parser/Lexer.x | 13 +-
compiler/parser/Parser.y.pp | 18 ++
compiler/parser/RdrHsSyn.lhs | 8 +-
compiler/prelude/TysWiredIn.lhs | 7 +-
compiler/rename/RnBinds.lhs | 152 +++++++--
compiler/rename/RnEnv.lhs | 7 +-
compiler/rename/RnNames.lhs | 18 ++
compiler/rename/RnPat.lhs | 26 +-
compiler/rename/RnSource.lhs | 25 +-
compiler/typecheck/TcBinds.lhs | 172 +++++++----
compiler/typecheck/TcClassDcl.lhs | 18 +-
compiler/typecheck/TcDeriv.lhs | 3 +-
compiler/typecheck/TcEnv.lhs | 16 +-
compiler/typecheck/TcExpr.lhs | 12 +-
compiler/typecheck/TcForeign.lhs | 3 +-
compiler/typecheck/TcGenDeriv.lhs | 50 +--
compiler/typecheck/TcGenGenerics.lhs | 6 +-
compiler/typecheck/TcHsSyn.lhs | 40 ++-
compiler/typecheck/TcHsType.lhs | 3 +-
compiler/typecheck/TcInstDcls.lhs | 28 +-
compiler/typecheck/TcPat.lhs | 130 ++++++--
compiler/typecheck/TcPatSyn.lhs | 324 ++++++++++++++++++++
compiler/typecheck/TcPatSyn.lhs-boot | 16 +
compiler/typecheck/TcRnDriver.lhs | 15 +-
compiler/typecheck/TcRnMonad.lhs | 8 +-
compiler/typecheck/TcRnTypes.lhs | 33 +-
compiler/typecheck/TcSplice.lhs | 3 +-
compiler/typecheck/TcTyClsDecls.lhs | 2 +-
compiler/types/TypeRep.lhs | 10 +-
compiler/utils/UniqFM.lhs | 13 +
compiler/utils/UniqSet.lhs | 1 +
ghc/GhciTags.hs | 10 +-
testsuite/tests/driver/T4437.hs | 3 +-
testsuite/tests/ghc-api/T6145.hs | 10 +-
testsuite/tests/{annotations => patsyn}/Makefile | 0
testsuite/tests/patsyn/should_compile/.gitignore | 9 +
.../should_compile/Makefile | 0
testsuite/tests/patsyn/should_compile/all.T | 9 +
testsuite/tests/patsyn/should_compile/bidir.hs | 6 +
testsuite/tests/patsyn/should_compile/ex-num.hs | 9 +
testsuite/tests/patsyn/should_compile/ex-prov.hs | 12 +
testsuite/tests/patsyn/should_compile/ex-view.hs | 12 +
testsuite/tests/patsyn/should_compile/ex.hs | 13 +
.../tests/patsyn/should_compile/incomplete.hs | 11 +
testsuite/tests/patsyn/should_compile/num.hs | 6 +
testsuite/tests/patsyn/should_compile/overlap.hs | 9 +
testsuite/tests/patsyn/should_compile/univ.hs | 11 +
.../should_compile => patsyn/should_fail}/Makefile | 0
testsuite/tests/patsyn/should_fail/all.T | 3 +
testsuite/tests/patsyn/should_fail/mono.hs | 7 +
testsuite/tests/patsyn/should_fail/mono.stderr | 12 +
testsuite/tests/patsyn/should_fail/unidir.hs | 4 +
testsuite/tests/patsyn/should_fail/unidir.stderr | 4 +
testsuite/tests/patsyn/should_run/.gitignore | 7 +
.../should_compile => patsyn/should_run}/Makefile | 0
testsuite/tests/patsyn/should_run/all.T | 3 +
testsuite/tests/patsyn/should_run/eval.hs | 22 ++
testsuite/tests/patsyn/should_run/eval.stdout | 7 +
testsuite/tests/patsyn/should_run/ex-prov-run.hs | 21 ++
.../should_run/ex-prov-run.stdout} | 0
testsuite/tests/patsyn/should_run/match.hs | 21 ++
testsuite/tests/patsyn/should_run/match.stdout | 5 +
utils/ghctags/Main.hs | 5 +-
99 files changed, 2324 insertions(+), 484 deletions(-)
Diff suppressed because of size. To see it, use:
git diff-tree --root --patch-with-stat --no-color --find-copies-harder --ignore-space-at-eol --cc 4f8369bf47d27b11415db251e816ef1a2e1eb3d8
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