38 lines
1,013 B
Haskell
38 lines
1,013 B
Haskell
module Main (main) where
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import Text.Parsec
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import Lib (exprparser, evaluate, replaceVars)
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import Data.Map (Map)
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import qualified Data.Map as Map
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import Data.Ratio
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import System.IO
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main :: IO ()
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main = ioLoop
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precision = 5 :: Int
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showRatio :: Int -> Rational -> String
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showRatio p r = (if (r < 0) then "-" else "") ++ prepoint_digits ++ "." ++ postpoint_digits
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where
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prepoint_digits = init . show . round $ (r * 10)
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postpoint_digits = (take p) . (drop (length prepoint_digits)) . show . round $ (r * 10^p)
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useResult (Right e) = (showRatio precision) . evaluate $ replaceVars e vars
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useResult (Left e) = show e
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vars :: Map String Rational
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vars = Map.fromList [("pi", 245850922 % 78256779), ("e", 271801 % 99990)]
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ioLoop :: IO ()
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ioLoop = do done <- isEOF
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if done
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then putStrLn "Quit!"
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else do inp <- getLine
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let expr = parse exprparser "<stdin>" inp
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putStrLn . useResult $ expr
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ioLoop
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