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| author | Vladislav Zavialov <vlad.z.4096@gmail.com> | 2019-12-02 23:10:33 +0300 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2019-12-05 16:07:49 -0500 |
| commit | 3354c68ec6c90bbccc0f361aa7973eeb75ea229c (patch) | |
| tree | b9c5e2f9627b25b6d7bdf745b281b6771b8d5990 /compiler/utils/Outputable.hs | |
| parent | c4ca29c796fa86ad9d5cd4dfa1a5cdd4e0565fb0 (diff) | |
| download | haskell-3354c68ec6c90bbccc0f361aa7973eeb75ea229c.tar.gz | |
Pretty-printing of the * kind
Before this patch, GHC always printed the * kind unparenthesized.
This led to two issues:
1. Sometimes GHC printed invalid or incorrect code.
For example, GHC would print: type F @* x = x
when it meant to print: type F @(*) x = x
In the former case, instead of a kind application we were getting a
type operator (@*).
2. Sometimes GHC printed kinds that were correct but hard to read.
Should Either * Int be read as Either (*) Int
or as (*) Either Int ?
This depends on whether -XStarIsType is enabled, but it would be
easier if we didn't have to check for the flag when reading the code.
We can solve both problems by assigning (*) a different precedence. Note
that Haskell98 kinds are not affected:
((* -> *) -> *) -> * does NOT become (((*) -> (*)) -> (*)) -> (*)
The parentheses are added when (*) is used in a function argument
position:
F * * * becomes F (*) (*) (*)
F A * B becomes F A (*) B
Proxy * becomes Proxy (*)
a * -> * becomes a (*) -> *
Diffstat (limited to 'compiler/utils/Outputable.hs')
| -rw-r--r-- | compiler/utils/Outputable.hs | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/compiler/utils/Outputable.hs b/compiler/utils/Outputable.hs index bbc365b774..0dda99020f 100644 --- a/compiler/utils/Outputable.hs +++ b/compiler/utils/Outputable.hs @@ -28,7 +28,7 @@ module Outputable ( semi, comma, colon, dcolon, space, equals, dot, vbar, arrow, larrow, darrow, arrowt, larrowt, arrowtt, larrowtt, lparen, rparen, lbrack, rbrack, lbrace, rbrace, underscore, - blankLine, forAllLit, kindType, bullet, + blankLine, forAllLit, bullet, (<>), (<+>), hcat, hsep, ($$), ($+$), vcat, sep, cat, @@ -91,7 +91,7 @@ import GhcPrelude import {-# SOURCE #-} DynFlags( DynFlags, hasPprDebug, hasNoDebugOutput, targetPlatform, pprUserLength, pprCols, - useUnicode, useUnicodeSyntax, useStarIsType, + useUnicode, useUnicodeSyntax, shouldUseColor, unsafeGlobalDynFlags, shouldUseHexWordLiterals ) import {-# SOURCE #-} Module( UnitId, Module, ModuleName, moduleName ) @@ -649,12 +649,6 @@ rbrace = docToSDoc $ Pretty.rbrace forAllLit :: SDoc forAllLit = unicodeSyntax (char '∀') (text "forall") -kindType :: SDoc -kindType = sdocWithDynFlags $ \dflags -> - if useStarIsType dflags - then unicodeSyntax (char '★') (char '*') - else text "Type" - bullet :: SDoc bullet = unicode (char '•') (char '*') |