59 lines
1.5 KiB
Haskell
59 lines
1.5 KiB
Haskell
{-# LANGUAGE TemplateHaskell #-}
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{-|
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Module : GHCup.Utils.String.QQ
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Description : String quasi quoters
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Copyright : (c) Audrey Tang <audreyt@audreyt.org> 2019, Julian Ospald <hasufell@posteo.de> 2020
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License : LGPL-3.0
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Maintainer : hasufell@hasufell.de
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Stability : experimental
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Portability : POSIX
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QuasiQuoter for non-interpolated strings, texts and bytestrings.
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The "s" quoter contains a multi-line string with no interpolation at all,
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except that the leading newline is trimmed and carriage returns stripped.
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@
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{-\# LANGUAGE QuasiQuotes #-}
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import Data.Text (Text)
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import Data.String.QQ
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foo :: Text -- "String", "ByteString" etc also works
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foo = [s|
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Well here is a
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multi-line string!
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|]
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@
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Any instance of the IsString type is permitted.
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(For GHC versions 6, write "[$s||]" instead of "[s||]".)
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-}
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module GHCup.Utils.String.QQ
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( s
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)
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where
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import Data.Char
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import GHC.Exts ( IsString(..) )
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import Language.Haskell.TH.Quote
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-- | QuasiQuoter for a non-interpolating ASCII IsString literal.
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-- The pattern portion is undefined.
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s :: QuasiQuoter
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s = QuasiQuoter
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(\s' -> case and $ fmap isAscii s' of
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True -> (\a -> [|fromString a|]) . trimLeadingNewline . removeCRs $ s'
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False -> fail "Not ascii"
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)
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(error "Cannot use q as a pattern")
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(error "Cannot use q as a type")
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(error "Cannot use q as a dec")
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where
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removeCRs = filter (/= '\r')
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trimLeadingNewline ('\n' : xs) = xs
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trimLeadingNewline xs = xs
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