commit d12ffc4f58768fd226930874edd98e4e4cd7c062
Author: Yann Esposito (Yogsototh) <Yann.Esposito@gmail.com>
Date:   Tue Jul 16 23:04:20 2013 +0200

    first commit

diff --git a/y.hs b/y.hs
new file mode 100644
index 0000000..4343646
--- /dev/null
+++ b/y.hs
@@ -0,0 +1,114 @@
+module Main where
+
+import Data.List (foldl')
+import Text.ParserCombinators.Parsec hiding (spaces)
+import System.Environment   (getArgs)
+
+data LispVal = Atom         String
+             | List         [LispVal]
+             | DottedList   [LispVal] LispVal
+             | Number       Integer
+             | String       String
+             | Bool         Bool
+             deriving (Show)
+
+symbol :: Parser Char
+symbol = oneOf "!#$%&|*+-/:<=>?@^_~"
+
+spaces :: Parser ()
+spaces = skipMany1 space
+
+parseString :: Parser LispVal
+parseString = do
+    char '"'
+    x <- many (    (char '\\' >> char 'n' >> return '\n')
+               <|> (char '\\' >> char 'r' >> return '\r')
+               <|> (char '\\' >> char 't' >> return '\t')
+               <|> (char '\\' >> anyChar)
+               <|> noneOf "\""
+               )
+    char '"'
+    return $ String x
+
+parseAtom :: Parser LispVal
+parseAtom = do
+    first <- letter <|> symbol
+    rest <- many (letter <|> digit <|> symbol)
+    let atom = first:rest
+    return $ case atom of
+                "#vrai" -> Bool True
+                "#faux" -> Bool False
+                _       -> Atom atom
+
+numFromBase n str = foldl' traiteNombre 0 str
+    where
+        traiteNombre acc v = acc*n + chiffre
+            where chiffre = case v of
+                            '0' -> 0
+                            '1' -> 1
+                            '2' -> 2
+                            '3' -> 3
+                            '4' -> 4
+                            '5' -> 5
+                            '6' -> 6
+                            '7' -> 7
+                            '8' -> 8
+                            '9' -> 9
+                            'A' -> 10
+                            'B' -> 11
+                            'C' -> 12
+                            'D' -> 13
+                            'E' -> 14
+                            'F' -> 15
+                            'a' -> 10
+                            'b' -> 11
+                            'c' -> 12
+                            'd' -> 13
+                            'e' -> 14
+                            'f' -> 15
+
+parseBaseSpecifiedNumber :: Parser Integer
+parseBaseSpecifiedNumber = do
+    _ <- char '#'
+    numtype <- oneOf "bdox"
+    (base,str) <- case numtype of
+                    'b' -> do
+                        numstr <- many1 (oneOf "01")
+                        return (2,numstr)
+                    'o' -> do
+                        numstr <- many1 (oneOf "01234567")
+                        return (8,numstr)
+                    'd' -> do
+                        numstr <- many1 (oneOf "0123456789")
+                        return (10,numstr)
+                    'x' -> do
+                        numstr <- many1 (oneOf "0123456789ABCDEFabcdef")
+                        return (16,numstr)
+    return $ numFromBase base str
+
+parseSimpleNumber :: Parser Integer
+parseSimpleNumber = do
+    numStr <- many1 digit
+    return (read numStr)
+
+parseNumber :: Parser LispVal
+parseNumber = do
+    number <-     parseSimpleNumber
+              <|> parseBaseSpecifiedNumber
+    return (Number number)
+
+parseExpr :: Parser LispVal
+parseExpr = parseString
+        <|> parseNumber
+        <|> parseAtom
+
+
+readExpr :: String -> String
+readExpr input = case parse parseExpr "lisp" input of
+                    Left  err -> "No match: " ++ show err
+                    Right val -> show val
+
+main :: IO ()
+main = do
+    args <- getArgs
+    putStrLn (readExpr (args !!0))