[Haskell-cafe] 1 = 0?
tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk
Tue Jun 17 10:54:27 UTC 2014
On Tue, Jun 17, 2014 at 03:25:10AM -0700, Alexey Muranov wrote:
> Is this the expected behavior that
> 1 = 0
> does not raise any error? What does this mean?
I guess it's an irrefutable pattern match that doesn't bind any variables,
so you can never see it fair. Cf
Prelude> let (x, 1) = (2,3)
*** Exception: <interactive>:7:5-18: Irrefutable pattern failed for pattern
*** (x, 1)
Prelude> let (x, 3) = (2,3)
I'll let someone more knowledgeable comment on why it's a good idea not to
prevent this kind of thing.
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