On Wed, Apr 02, 2014 at 09:51:46AM -0400, Edward Kmett wrote:
Consider something like
data Foo a = Foo !Int !a
The data constructor Foo needs to be strict in its arguments, so it'd need Seq Int and Seq a. Seq Int would be resolved by the environment, but Seq a would need to come from somewhere.
data Seq a => Foo a = Foo !Int !a
Oh right, I didn't realise that's what you meant by "patterns". I assumed you were talking about let or function definitions.
On Wed, Apr 2, 2014 at 3:08 AM, Tom Ellis < tom-lists-haskell-cafe-2013@jaguarpaw.co.uk> wrote:
On Tue, Apr 01, 2014 at 05:32:45PM -0400, Edward Kmett wrote:
Unfortunately the old class based solution also carries other baggage, like the old data type contexts being needed in the language for bang patterns. :(
Can you explain why that is so? I don't understand.