[Haskell-beginners] About ! before a type signature

[Bob Ippolito]

That declares those fields to be strict. See also
http://www.haskell.org/haskellwiki/Performance/Data_types

On Friday, June 6, 2014, Song Zhang <vxanica at gmail.com> wrote:

> This is about syntax of Haskell.
> I am reading the source code of Yampa. I find that a definition like the
> following
>
> data SF' a b where
>     SFArr   :: !(DTime -> a -> Transition a b) -> !(FunDesc a b) -> SF' a b
>
>
> in Yampa.hs.
>
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