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Diffstat (limited to 'compiler/Language/Haskell/Syntax/Extension.hs')
| -rw-r--r-- | compiler/Language/Haskell/Syntax/Extension.hs | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/compiler/Language/Haskell/Syntax/Extension.hs b/compiler/Language/Haskell/Syntax/Extension.hs index 278b8aa99e..8d8eadf135 100644 --- a/compiler/Language/Haskell/Syntax/Extension.hs +++ b/compiler/Language/Haskell/Syntax/Extension.hs @@ -706,3 +706,16 @@ type LHsToken tok p = XRec p (HsToken tok) data HsToken (tok :: Symbol) = HsTok deriving instance KnownSymbol tok => Data (HsToken tok) + +type LHsUniToken tok utok p = XRec p (HsUniToken tok utok) + +-- With UnicodeSyntax, there might be multiple ways to write the same token. +-- For example an arrow could be either "->" or "→". This choice must be +-- recorded in order to exactprint such tokens, +-- so instead of HsToken "->" we introduce HsUniToken "->" "→". +-- +-- See also IsUnicodeSyntax in GHC.Parser.Annotation; we do not use here to +-- avoid a dependency. +data HsUniToken (tok :: Symbol) (utok :: Symbol) = HsNormalTok | HsUnicodeTok + +deriving instance (KnownSymbol tok, KnownSymbol utok) => Data (HsUniToken tok utok) |