-- read http://learnyouahaskell.com/types-and-typeclasses

:t compare
compare :: Ord a => a -> a -> Ordering
Prelude> compare 3 4
LT
Prelude> compare 3 3
EQ
Prelude> compare 3 2
GT
Prelude> show 3
"3"
Prelude> show True
"True"
Prelude> :t show
show :: Show a => a -> String

Prelude> read "True"

<interactive>:1:1:
    Ambiguous type variable `a0' in the constraint:
      (Read a0) arising from a use of `read'
    Probable fix: add a type signature that fixes these type variable(s)
    In the expression: read "True"
    In an equation for `it': it = read "True"
Prelude> read "True" :: Boolean

<interactive>:1:16:
    Not in scope: type constructor or class `Boolean'
Prelude> read "True" :: Bool
True
Prelude> :t read
read :: Read a => String -> a

Prelude> 3.2 + length [1,2,3]

<interactive>:1:1:
    No instance for (Fractional Int)
      arising from the literal `3.2'
    Possible fix: add an instance declaration for (Fractional Int)
    In the first argument of `(+)', namely `3.2'
    In the expression: 3.2 + length [1, 2, 3]
    In an equation for `it': it = 3.2 + length [1, 2, 3]

Prelude> 3.2 + fromIntegral (length [1,2,3] )
6.2

Prelude> :t fromIntegral
fromIntegral :: (Num b, Integral a) => a -> b