Base.hs

module Calculator.Prim.Base where

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import           Text.ParserCombinators.Parsec

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import           Control.Applicative           ((<$>))
import           Control.Monad                 (liftM2)

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type Number = Double

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parseNumber :: Parser Number
parseNumber = read <$> do
  dec <- many1 digit
  flt <- option "" (liftM2 (:) (char '.') (many1 digit))
  if null flt
    then return dec
    else return $ dec ++ flt

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parseId :: Parser String
parseId = (liftM2 (:) letter (many (letter <|> digit)))

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