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Use maybeM in Data.Scientific.Exts to fail parsing.

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This commit is contained in:
Rob Rix 2018-04-24 11:48:39 -04:00
parent 812adece0f
commit 3e3f21c1d7
1 changed files with 5 additions and 6 deletions
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11
src/Data/Scientific/Exts.hs
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@ -3,16 +3,15 @@ module Data.Scientific.Exts
, parseScientific , parseScientific
) where ) where
import Prelude hiding (filter, null, takeWhile)
import Control.Applicative import Control.Applicative
import Control.Monad import Control.Monad hiding (fail)
import Data.Attoparsec.ByteString.Char8 import Data.Attoparsec.ByteString.Char8
import Data.ByteString.Char8 hiding (readInt, takeWhile) import Data.ByteString.Char8 hiding (readInt, takeWhile)
import Data.Char (isOctDigit) import Data.Char (isOctDigit)
import Data.Scientific import Data.Scientific
import Data.Semigroup
import Numeric import Numeric
import Prelude hiding (fail, filter, null, takeWhile)
import Prologue hiding (null)
import Text.Read (readMaybe) import Text.Read (readMaybe)
parseScientific :: ByteString -> Either String Scientific parseScientific :: ByteString -> Either String Scientific
@ -38,9 +37,9 @@ parser = signed (choice [hex, oct, bin, dec]) where
-- The ending stanza. Note the explicit endOfInput call to ensure we haven't left any dangling input. -- The ending stanza. Note the explicit endOfInput call to ensure we haven't left any dangling input.
done = skipWhile (inClass "iIjJlL") *> endOfInput done = skipWhile (inClass "iIjJlL") *> endOfInput
-- Wrapper around readMaybe. Analogous to maybeFail in the Prologue, but no need to pull that in. -- Wrapper around readMaybe.
attempt :: Read a => String -> Parser a attempt :: Read a => String -> Parser a
attempt str = maybe (fail ("No parse: " <> str)) pure (readMaybe str) attempt str = maybeM (fail ("No parse: " <> str)) (readMaybe str)
-- Parse a hex value, leaning on the parser provided by Attoparsec. -- Parse a hex value, leaning on the parser provided by Attoparsec.
hex = fromIntegral <$> (string "0x" *> hexadecimal @Integer) hex = fromIntegral <$> (string "0x" *> hexadecimal @Integer)