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

[yi lu]

On Tue, Sep 24, 2013 at 6:54 PM, Lyndon Maydwell <maydwell at gmail.com> wrote:

> Looks like it's a convenience for building up a compositions of "Show"s.
>
> ShowS is indeed a synonym for a function. The type of shows alone isn't
> enough to figure out how it behaves exactly, but testing it out in GHCi is
> telling:
>
>
> > [Prelude] λ :i ShowS
> > type ShowS = String -> String -- Defined in `GHC.Show'
> > [Prelude] λ :i shows
> > shows :: Show a => a -> ShowS -- Defined in `GHC.Show'
> > [Prelude] λ shows "asdf" "qwer"
> > "\"asdf\"qwer"
>
> I don't know the meaning of this result.



>
> On Tue, Sep 24, 2013 at 8:15 PM, yi lu <zhiwudazhanjiangshi at gmail.com>wrote:
>
>> 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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