diff options
Diffstat (limited to 'main.hs')
| -rw-r--r-- | main.hs | 45 |
1 files changed, 44 insertions, 1 deletions
@@ -1,2 +1,45 @@ +import System.Environment +import Data.Char + +data TokenType = Number | Add | Sub | Mul | Exp | Equal deriving (Show) +data Token = Token TokenType Float deriving (Show) + main = do - putStr "HelloWorld" + args <- getArgs + -- putStr $ show args + let l = lexer $ (head args) + putStrLn $ show l + + +lexer :: String -> [Token] +lexer "" = [] +lexer (c:rest) + | c == ' ' = lexer rest + | isDigit c = (Token Number (read (isolateFloat (c:rest)) :: Float)) : lexer (afterFloat (c:rest)) + | c == '+' = (Token Add 0.0) : lexer rest + | c == '-' = (Token Sub 0.0) : lexer rest + | c == '*' = (Token Mul 0.0) : lexer rest + | c == '^' = (Token Exp 0.0) : lexer rest + | c == '=' = (Token Equal 0.0) : lexer rest + + where isolateFloat :: String -> String + isolateFloat "" = "" + isolateFloat (c:cs) + | isDigit c = c : isolateFloat cs + | c == '.' = c : isolateFloat cs + | otherwise = "" + + afterFloat :: String -> String + afterFloat "" = "" + afterFloat (c:cs) + | isDigit c = afterFloat cs + | c == '.' = afterFloat cs + | otherwise = (c:cs) + + +-- parse :: Lexing -> SyntaxTree +-- parse s = 2 +-- +-- +-- eval :: SyntaxTree -> Maybe [Float] +-- eval _ = 0.0 |
