Adds Builder Show instance

[elikoga]

As mentioned in #47 Builder and friends should have Show instances.

I have added a Show instance inspired by the Show instance of Set. If it should be styled differently just mention it.

If I should add any more instances just mention it.

[Bodigrim]

I agree with the proposed approach in general. However lazyByteString "12345" requires {-# LANGUAGE OverloadedStrings #-} enabled. How do you feel about string8 instead of lazyByteString?

[fumieval]

Why not just "12345"? Other Show ByteString instances require OverloadedStrings as well.

[Bodigrim]

@fumieval even better, I forgot that there is instance IsString Builder. Could you possibly suggest which other data types from Data.ByteString.Builder.* may benefit from having Show instance?

[elikoga]

Done

[fumieval]

Could you possibly suggest which other data types from Data.ByteString.Builder.* may benefit from having Show instance

There are Next, FixedPrim and BoundedPrim, but none of them has a reasonable Show instance.

[elikoga]

What would be reasonable Show instances for Next, FixedPrim and BoundedPrim.

I can't think of any for FixedPrim and BoundedPrim and Next doesn't seem easy either.

[elikoga]

One idea for a FixedPrim a and BoundedPrim a instance would be to only show their Fixed/Bounded size while not showing the IO action dependent on a.

[fumieval]

@elikoga no, we should not add Show instances to them.

[Bodigrim]

Thanks, @elikoga!