[Haskell-cafe] Why isn't pattern matching lazy by default?
lemming at henning-thielemann.de
Wed Sep 19 11:24:43 EDT 2007
On Wed, 19 Sep 2007, Peter Verswyvelen wrote:
> I got stuck with an endless loop when trying to split a stream into a pair of
> two streams (a kind of reactive if/then/else). Luckily I first read the
> Haskell School of Expression so I remembered that pattern matching is not
> lazy and this could be the cause, which it was (I had to replace (x:xs) by
> Now why isn't pattern matching lazy by default? This seems odd for a newbie
> since everything else is lazy by default.
It's even more confusing that pattern matching in 'let' _is_ lazy.
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