You can see it on Hackage. Just click on Synopsis here: http://hackage.haskell.org/packages/archive/base/4.4.0.0/doc/html/Prelude.ht... . Also, GHCi can tell you that for any module using :browse. $ ghci GHCi, version 7.0.3: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude> :browse Prelude ($!) :: (a -> b) -> a -> b (!!) :: [a] -> Int -> a ($) :: (a -> b) -> a -> b (&&) :: Bool -> Bool -> Bool (++) :: [a] -> [a] -> [a] (.) :: (b -> c) -> (a -> b) -> a -> c (=<<) :: Monad m => (a -> m b) -> m a -> m b data Bool = False | True class Bounded a where minBound :: a maxBound :: a data Char = GHC.Types.C# GHC.Prim.Char# data Double = GHC.Types.D# GHC.Prim.Double# data Either a b = Left a | Right b class Enum a where succ :: a -> a pred :: a -> a toEnum :: Int -> a fromEnum :: a -> Int enumFrom :: a -> [a] enumFromThen :: a -> a -> [a] enumFromTo :: a -> a -> [a] enumFromThenTo :: a -> a -> a -> [a] class Eq a where (==) :: a -> a -> Bool (/=) :: a -> a -> Bool type FilePath = String data Float = GHC.Types.F# GHC.Prim.Float# class Fractional a => Floating a where pi :: a exp :: a -> a sqrt :: a -> a log :: a -> a (**) :: a -> a -> a logBase :: a -> a -> a sin :: a -> a tan :: a -> a cos :: a -> a asin :: a -> a atan :: a -> a acos :: a -> a sinh :: a -> a tanh :: a -> a cosh :: a -> a asinh :: a -> a atanh :: a -> a acosh :: a -> a class Num a => Fractional a where (/) :: a -> a -> a recip :: a -> a fromRational :: Rational -> a class Functor f where fmap :: (a -> b) -> f a -> f b (GHC.Base.<$) :: a -> f b -> f a newtype IO a = GHC.Types.IO (GHC.Prim.State# GHC.Prim.RealWorld -> (# GHC.Prim.State# GHC.Prim.RealWorld, a #)) type IOError = GHC.IO.Exception.IOException data Int = GHC.Types.I# GHC.Prim.Int# data Integer = integer-gmp:GHC.Integer.Type.S# GHC.Prim.Int# | integer-gmp:GHC.Integer.Type.J# GHC.Prim.Int# GHC.Prim.ByteArray# class (Real a, Enum a) => Integral a where quot :: a -> a -> a rem :: a -> a -> a div :: a -> a -> a mod :: a -> a -> a quotRem :: a -> a -> (a, a) divMod :: a -> a -> (a, a) toInteger :: a -> Integer data Maybe a = Nothing | Just a class Monad m where (>>=) :: m a -> (a -> m b) -> m b (>>) :: m a -> m b -> m b return :: a -> m a fail :: String -> m a class (Eq a, Show a) => Num a where (+) :: a -> a -> a (*) :: a -> a -> a (-) :: a -> a -> a negate :: a -> a abs :: a -> a signum :: a -> a fromInteger :: Integer -> a class Eq a => Ord a where compare :: a -> a -> Ordering (<) :: a -> a -> Bool (>=) :: a -> a -> Bool (>) :: a -> a -> Bool (<=) :: a -> a -> Bool max :: a -> a -> a min :: a -> a -> a data Ordering = LT | EQ | GT type Rational = GHC.Real.Ratio Integer class Read a where readsPrec :: Int -> ReadS a readList :: ReadS [a] GHC.Read.readPrec :: Text.ParserCombinators.ReadPrec.ReadPrec a GHC.Read.readListPrec :: Text.ParserCombinators.ReadPrec.ReadPrec [a] type ReadS a = String -> [(a, String)] class (Num a, Ord a) => Real a where toRational :: a -> Rational class (RealFrac a, Floating a) => RealFloat a where floatRadix :: a -> Integer floatDigits :: a -> Int floatRange :: a -> (Int, Int) decodeFloat :: a -> (Integer, Int) encodeFloat :: Integer -> Int -> a exponent :: a -> Int significand :: a -> a scaleFloat :: Int -> a -> a isNaN :: a -> Bool isInfinite :: a -> Bool isDenormalized :: a -> Bool isNegativeZero :: a -> Bool isIEEE :: a -> Bool atan2 :: a -> a -> a class (Real a, Fractional a) => RealFrac a where properFraction :: Integral b => a -> (b, a) truncate :: Integral b => a -> b round :: Integral b => a -> b ceiling :: Integral b => a -> b floor :: Integral b => a -> b class Show a where showsPrec :: Int -> a -> ShowS show :: a -> String showList :: [a] -> ShowS type ShowS = String -> String type String = [Char] (^) :: (Num a, Integral b) => a -> b -> a (^^) :: (Fractional a, Integral b) => a -> b -> a all :: (a -> Bool) -> [a] -> Bool and :: [Bool] -> Bool any :: (a -> Bool) -> [a] -> Bool appendFile :: FilePath -> String -> IO () asTypeOf :: a -> a -> a break :: (a -> Bool) -> [a] -> ([a], [a]) catch :: IO a -> (IOError -> IO a) -> IO a concat :: [[a]] -> [a] concatMap :: (a -> [b]) -> [a] -> [b] const :: a -> b -> a curry :: ((a, b) -> c) -> a -> b -> c cycle :: [a] -> [a] drop :: Int -> [a] -> [a] dropWhile :: (a -> Bool) -> [a] -> [a] either :: (a -> c) -> (b -> c) -> Either a b -> c elem :: Eq a => a -> [a] -> Bool error :: [Char] -> a even :: Integral a => a -> Bool filter :: (a -> Bool) -> [a] -> [a] flip :: (a -> b -> c) -> b -> a -> c foldl :: (a -> b -> a) -> a -> [b] -> a foldl1 :: (a -> a -> a) -> [a] -> a foldr :: (a -> b -> b) -> b -> [a] -> b foldr1 :: (a -> a -> a) -> [a] -> a fromIntegral :: (Integral a, Num b) => a -> b fst :: (a, b) -> a gcd :: Integral a => a -> a -> a getChar :: IO Char getContents :: IO String getLine :: IO String head :: [a] -> a id :: a -> a init :: [a] -> [a] interact :: (String -> String) -> IO () ioError :: IOError -> IO a iterate :: (a -> a) -> a -> [a] last :: [a] -> a lcm :: Integral a => a -> a -> a length :: [a] -> Int lex :: ReadS String lines :: String -> [String] lookup :: Eq a => a -> [(a, b)] -> Maybe b map :: (a -> b) -> [a] -> [b] mapM :: Monad m => (a -> m b) -> [a] -> m [b] mapM_ :: Monad m => (a -> m b) -> [a] -> m () maximum :: Ord a => [a] -> a maybe :: b -> (a -> b) -> Maybe a -> b minimum :: Ord a => [a] -> a not :: Bool -> Bool notElem :: Eq a => a -> [a] -> Bool null :: [a] -> Bool odd :: Integral a => a -> Bool or :: [Bool] -> Bool otherwise :: Bool print :: Show a => a -> IO () product :: Num a => [a] -> a putChar :: Char -> IO () putStr :: String -> IO () putStrLn :: String -> IO () read :: Read a => String -> a readFile :: FilePath -> IO String readIO :: Read a => String -> IO a readLn :: Read a => IO a readParen :: Bool -> ReadS a -> ReadS a reads :: Read a => ReadS a realToFrac :: (Real a, Fractional b) => a -> b repeat :: a -> [a] replicate :: Int -> a -> [a] reverse :: [a] -> [a] scanl :: (a -> b -> a) -> a -> [b] -> [a] scanl1 :: (a -> a -> a) -> [a] -> [a] scanr :: (a -> b -> b) -> b -> [a] -> [b] scanr1 :: (a -> a -> a) -> [a] -> [a] seq :: a -> b -> b sequence :: Monad m => [m a] -> m [a] sequence_ :: Monad m => [m a] -> m () showChar :: Char -> ShowS showParen :: Bool -> ShowS -> ShowS showString :: String -> ShowS shows :: Show a => a -> ShowS snd :: (a, b) -> b span :: (a -> Bool) -> [a] -> ([a], [a]) splitAt :: Int -> [a] -> ([a], [a]) subtract :: Num a => a -> a -> a sum :: Num a => [a] -> a tail :: [a] -> [a] take :: Int -> [a] -> [a] takeWhile :: (a -> Bool) -> [a] -> [a] uncurry :: (a -> b -> c) -> (a, b) -> c undefined :: a unlines :: [String] -> String until :: (a -> Bool) -> (a -> a) -> a -> a unwords :: [String] -> String unzip :: [(a, b)] -> ([a], [b]) unzip3 :: [(a, b, c)] -> ([a], [b], [c]) userError :: String -> IOError words :: String -> [String] writeFile :: FilePath -> String -> IO () zip :: [a] -> [b] -> [(a, b)] zip3 :: [a] -> [b] -> [c] -> [(a, b, c)] zipWith :: (a -> b -> c) -> [a] -> [b] -> [c] zipWith3 :: (a -> b -> c -> d) -> [a] -> [b] -> [c] -> [d] (||) :: Bool -> Bool -> Bool -- Felipe.