2 Mar
2001
2 Mar
'01
6:58 p.m.
Thu, 1 Mar 2001 12:25:33 +0100, S. Doaitse Swierstra <doaitse@cs.uu.nl> pisze:
From the Haskell manual I understand that pattern matching in "let"'s should be done lazily, so the addition of a collection of ~'s should not make a difference.
Toplevel ~ in let doesn't change anything. But nested ~'s do make a difference. When a variable of a pattern is evaluated, the whole pattern is matched. When you protect a subpattern by ~ deferring its matching and a variable from the subpattern is evaluated, again the whole subpattern is matched, unless its subsubpatterns are protected with their own ~'s etc. -- __("< Marcin Kowalczyk * qrczak@knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK