[Haskell-beginners] How to understand the type "ShowS"?

[yi lu]

Prelude> :i ShowS
type ShowS = String -> String     -- Defined in `GHC.Show'

It is a type of a function? I cannot understand this type, and don't know
how to create functions of this type.

And this function "shows"

Prelude> :i shows
shows :: Show a => a -> ShowS     -- Defined in `GHC.Show'

I don't know how this function works.

Yi
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