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λ> 1.5 == 1.5
True
λ> sin
sin :: Floating a => a -> a
λ> show 1234
"1234"
λ> show [1, 5]
"[1,5]"
λ> read "[1,5]"
*** Exception: Prelude.read: no parse
λ> :t read
read :: Read a => String -> a
λ> :t show
show :: Show a => a -> String
λ> (read "[1,5]")::[Int]
[1,5]
λ> (read "[1,5]")::[Double]
[1.0,5.0]
λ> (read "[1,5]")::[Char]
"*** Exception: Prelude.read: no parse
λ> :t 2
2 :: Num p => p
λ> :t (div 2 5)
(div 2 5) :: Integral a => a
λ> :t (div 2 500000000000000000000)
(div 2 500000000000000000000) :: Integral a => a
λ> :t (div 2 500000000000000000000000000000)
(div 2 500000000000000000000000000000) :: Integral a => a
λ> [ (x,y) | x <- [1..3], y <- [4..6]]
[(1,4),(1,5),(1,6),(2,4),(2,5),(2,6),(3,4),(3,5),(3,6)]
λ> map (\x -> x) [1..3]
[1,2,3]
λ> map (\x -> (map (\y -> (x,y)) [4..6])) [1..3]
[[(1,4),(1,5),(1,6)],[(2,4),(2,5),(2,6)],[(3,4),(3,5),(3,6)]]
λ> concat (map (\x -> (map (\y -> (x,y)) [4..6])) [1..3])
[(1,4),(1,5),(1,6),(2,4),(2,5),(2,6),(3,4),(3,5),(3,6)]
λ> foldr (\x r -> x == 0 || r) False [-5..5]
True
λ> foldr (\x r -> x == 0 || r) False [5..50]
False
λ> foldr (\x r -> (||) (x == 0) r) False [5..50]
False
λ> foldr (\x -> (|| x == 0)) False [5..50]
False
λ> foldr (\x -> (|| x == 0)) False [-5..5]
True
λ> foldr (\x -> (x == 0 ||)) False [-5..5]
True
λ> maximum []
*** Exception: Prelude.maximum: empty list
λ> foldr1 (+) []
*** Exception: Prelude.foldr1: empty list
λ> foldr1 (\_ x -> x) [1..10]
10
λ> foldl1 (\_ x -> x) [1..10]
10
λ> scanr (+) 0 [1..10]
[55,54,52,49,45,40,34,27,19,10,0]
λ> foldr (+) 0 [1..10]
55
λ> foldl (+) 0 [1..10]
55
λ> scanl (+) 0 [1..10]
[0,10,9,8,7,6,5,4,3,2,1]
λ> foldr (:) [] [1..10]
[1,2,3,4,5,6,7,8,9,10]
λ> scanr (:) [] [1..10]
[[1,2,3,4,5,6,7,8,9,10],[2,3,4,5,6,7,8,9,10],[3,4,5,6,7,8,9,10],[4,5,6,7,8,9,10],[5,6,7,8,9,10],[6,7,8,9,10],[7,8,9,10],[8,9,10],[9,10],[10],[]]
λ> Data.List.tails [1..10]
[[1,2,3,4,5,6,7,8,9,10],[2,3,4,5,6,7,8,9,10],[3,4,5,6,7,8,9,10],[4,5,6,7,8,9,10],[5,6,7,8,9,10],[6,7,8,9,10],[7,8,9,10],[8,9,10],[9,10],[10],[]]
λ> foldl (flip (:)) [] [1..10]
[10,9,8,7,6,5,4,3,2,1]
λ> scanl (+) 0 [1..10]
[0,1,3,6,10,15,21,28,36,45,55]
λ> scanl (flip (:)) [] [1..10]
[[],[1],[2,1],[3,2,1],[4,3,2,1],[5,4,3,2,1],[6,5,4,3,2,1],[7,6,5,4,3,2,1],[8,7,6,5,4,3,2,1],[9,8,7,6,5,4,3,2,1],[10,9,8,7,6,5,4,3,2,1]]
λ> scanl (\r x -> r ++ [x]) [] [1..10]
[[],[1],[1,2],[1,2,3],[1,2,3,4],[1,2,3,4,5],[1,2,3,4,5,6],[1,2,3,4,5,6,7],[1,2,3,4,5,6,7,8],[1,2,3,4,5,6,7,8,9],[1,2,3,4,5,6,7,8,9,10]]
λ> Data.List.inits [1..10]
[[],[1],[1,2],[1,2,3],[1,2,3,4],[1,2,3,4,5],[1,2,3,4,5,6],[1,2,3,4,5,6,7],[1,2,3,4,5,6,7,8],[1,2,3,4,5,6,7,8,9],[1,2,3,4,5,6,7,8,9,10]]
λ> scanr (:) [] [1..10]
[[1,2,3,4,5,6,7,8,9,10],[2,3,4,5,6,7,8,9,10],[3,4,5,6,7,8,9,10],[4,5,6,7,8,9,10],[5,6,7,8,9,10],[6,7,8,9,10],[7,8,9,10],[8,9,10],[9,10],[10],[]]
λ> scanr (+) 0 [1..10]
[55,54,52,49,45,40,34,27,19,10,0]
λ> zip [1..5] [2..6]
[(1,2),(2,3),(3,4),(4,5),(5,6)]
λ> zip [1..5] [2..6]
[(1,2),(2,3),(3,4),(4,5),(5,6)]
λ> unzip (zip [1..5] [2..6])
([1,2,3,4,5],[2,3,4,5,6])
λ> zipWith (*) [1..5] [2..6]
[2,6,12,20,30]
λ> zipWith (*) [1..5] [2..6]
[2,6,12,20,30]
λ> zip [1..5] [2..6]
[(1,2),(2,3),(3,4),(4,5),(5,6)]
λ> takeWhile (<5) [1..10]
[1,2,3,4]
λ> Prelude.takeWhile (const True) [1..10]
[1,2,3,4,5,6,7,8,9,10]
λ> takeWhile (<5) [1..10]
[]
λ> takeWhile (<5) [1..10]
[1,2,3,4]
λ> dropWhile (<5) [1..10]
[5,6,7,8,9,10]
λ> Prelude.dropWhile (const True) [1..10]
[]
λ> Prelude.dropWhile (const False) [1..10]
[1,2,3,4,5,6,7,8,9,10]
λ> takeWhile odd [1..5]
[1]
λ> dropWhile odd [1..5]
[2,3,4,5]
λ> dropWhile (<5) [1..10]
[5,6,7,8,9,10]
λ>