ghci> :t ([1,2,3], "abc")
([1,2,3], "abc") :: Num a => ([a], String)
ghci> (,) 1 2											-- constructor de date
(1,2)

ghci> :t f
f :: (a, [b]) -> a

ghci> :i (,)
type (,) :: * -> * -> *									-- constructor de tip
data (,) a b = (,) a b									-- constructor de date
        -- Defined in `GHC.Tuple.Prim'
...
ghci> :t []												-- constructor de tip
[] :: [a]

ghci> :t g
g :: [Integer] -> Integer

-- implementare care întoarce lista
ghci> search 3 d
"c"
ghci> search 2 d
"bd"
ghci> search 2 d
'b'
ghci> search 3 d
'c'
ghci> search 5 d
*** Exception: Prelude.head: empty list

-- impelmentare care întoarce Maybe a
ghci> search 3 d
Just 'c'
ghci> search 5 d
Nothing
ghci> :i Maybe
type Maybe :: * -> *
data Maybe a = Nothing | Just a
        -- Defined in `GHC.Maybe'
...
ghci> :k Bool
Bool :: *
ghci> :k String
String :: *

ghci> :k []
[] :: * -> *
ghci> :k [a]
[a] :: *
ghci> :k (,)
(,) :: * -> * -> *
ghci> :k (,,,)
(,,,) :: * -> * -> * -> * -> *

ghci> :k (->)
(->) :: * -> * -> *
ghci> :t elem
elem :: (Foldable t, Eq a) => a -> t a -> Bool
ghci> elem 5 [1,2,3,4,5,6]
True
ghci> :t elem
elem :: (Foldable t, Eq a) => a -> t a -> Bool