Use `showVal` to print with show rather than the default

[my-scheme.git] / app / Main.hs

diff --git a/app/Main.hs b/app/Main.hs
index 0c0d29c7a4acf3351624522b2e96080c4b4c1fc5..78f37ea4132604b9ee481dba40f65ab0e5738be3 100644 (file)
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -2,14 +2,15 @@ module Main where
 import Control.Monad
 import Text.ParserCombinators.Parsec hiding (spaces)
 import System.Environment
 import Control.Monad
 import Text.ParserCombinators.Parsec hiding (spaces)
 import System.Environment

+import Numeric

 
 data LispVal = Atom String
              | List [LispVal]
              | DottedList [LispVal] LispVal
              | Number Integer
              | String String
 
 data LispVal = Atom String
              | List [LispVal]
              | DottedList [LispVal] LispVal
              | Number Integer
              | String String

+             | Character Char

              | Bool Bool
              | Bool Bool

-             deriving Show

 
 symbol :: Parser Char
 symbol = oneOf "!#$%&|*+-/:<=>?@^_~"
 
 symbol :: Parser Char
 symbol = oneOf "!#$%&|*+-/:<=>?@^_~"


@@ -17,15 +18,29 @@ symbol = oneOf "!#$%&|*+-/:<=>?@^_~"
 spaces :: Parser ()
 spaces = skipMany space
 
 spaces :: Parser ()
 spaces = skipMany space
 

+nonPrintableChar :: Parser Char
+nonPrintableChar = do c <- char '\\' >> oneOf "\\nrtf"
+                      return $ case c of '\\' -> '\\'
+                                         'n'  -> '\n'
+                                         'r'  -> '\r'
+                                         't'  -> '\t'
+                                         'f'  -> '\f'
+
+parseCharacter :: Parser LispVal
+parseCharacter = do char '\''
+                    c <- noneOf ['\\', '\''] <|> try singleQuote <|> try nonPrintableChar
+                    char '\''
+                    return $ Character c
+                 where
+                    singleQuote = char '\\' >> char '\''
+

 parseString :: Parser LispVal
 parseString = do char '"'
                  x <- many innerChar
                  char '"'
                  return $ String x
 parseString :: Parser LispVal
 parseString = do char '"'
                  x <- many innerChar
                  char '"'
                  return $ String x

-              where innerChar = noneOf ['\\', '\"'] <|> escapeChar
-                    escapeChar = do char '\\'
-                                    c <- oneOf "\""
-                                    return $ '\"'
+              where innerChar = noneOf ['\\', '"'] <|> try doubleQuote <|> try nonPrintableChar
+                    doubleQuote = char '\\' >> char '"'

 
 parseAtom :: Parser LispVal
 parseAtom = do
 
 parseAtom :: Parser LispVal
 parseAtom = do


@@ -38,19 +53,61 @@ parseAtom = do
                 _    -> Atom atom
 
 parseNumber :: Parser LispVal
                 _    -> Atom atom
 
 parseNumber :: Parser LispVal

-parseNumber = do ds <- many1 digit
-                 let a = read ds
+parseNumber = do toNum <- radix
+                 ds <- many1 digit
+                 let ((a,_):_) = toNum ds

                  return $ Number a
                  return $ Number a

+              where radix = do r <- try (char '#' >> oneOf "bodx") <|> return 'd'
+                               return $ case r of
+                                           'd' -> readDec
+                                           'x' -> readHex
+                                           'o' -> readOct
+                                           'b' -> readInt 2 (\x -> elem x "01") (read . (:[]))
+
+parseList :: Parser LispVal
+parseList = liftM List $ sepBy parseExpr spaces
+
+parseDottedList :: Parser LispVal
+parseDottedList = do
+    head <- endBy parseExpr spaces
+    tail <- char '.' >> spaces >> parseExpr
+    return $ DottedList head tail
+
+parseQuoted :: Parser LispVal
+parseQuoted = do
+    char '\''
+    x <- parseExpr
+    return $ List [Atom "quote", x]

 
 parseExpr :: Parser LispVal
 parseExpr = parseString
 
 parseExpr :: Parser LispVal
 parseExpr = parseString

-        <|> parseAtom

         <|> parseNumber
         <|> parseNumber

+        <|> parseAtom
+        <|> try parseCharacter
+        <|> parseQuoted
+        <|> do char '('
+               x <- try parseList <|> parseDottedList
+               char ')'
+               return x

 
 readExpr :: String -> String
 readExpr input = case parse parseExpr "lisp" input of
     Left err -> "No match: " ++ show err
 
 readExpr :: String -> String
 readExpr input = case parse parseExpr "lisp" input of
     Left err -> "No match: " ++ show err

-    Right val -> "Found value: " ++ show val
+    Right val -> "Found value: " ++ showVal val
+
+instance Show LispVal where show = showVal
+showVal :: LispVal -> String
+showVal (Atom atom)   = atom
+showVal (List list)   = "(" ++ unwordsList list ++ ")"
+showVal (DottedList head tail)   = "(" ++ unwordsList head ++ " . " ++ showVal tail ++ ")"
+showVal (Number n)    = show n
+showVal (String str)  = "\"" ++ str ++ "\""
+showVal (Character c) = "'" ++ [c] ++ "'"
+showVal (Bool True)   = "#t"
+showVal (Bool False)  = "#f"
+
+unwordsList :: [LispVal] -> String
+unwordsList = unwords . map showVal

 
 main :: IO ()
 main = do
 
 main :: IO ()
 main = do