[R] Can we get rid of && and ||?
GB
gb at stat.umu.se
Thu Apr 13 15:58:28 CEST 2000
Bill,
thank you for the lesson! Just one question:
[snip]
> I think you miss the point quite seriously.
No and yes.
> Under the present semantics
> in 'a & b' *both* a and b are *guaranteed* unconditionally to be evaluated,
I didn't miss this.
> and in a lazy evaluation language, especially, that unconditional evaluation
> can be vital.
I missed this. And I don't quite understand it (yet). In 'a && b', why
would it be vital to evaluate b if a is FALSE? Of course, in a
construct like 'a && (b <- c)' it would, but isn't 'b <- c; a && b' more
readible and to be recommended? (Or does the former code execute faster?)
I think I need a good example here. Can you give me one?
Once again, thanks!
Göran
----------------------------------------------------------
Göran Broström tel: +46 90 786-5223
Department of Statistics
Umeå University
SE-90187 Umeå, Sweden email: gb at stat.umu.se
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