[eeps] EEP XXX: Pattern-test operator

David Mercer <>
Mon Apr 30 03:59:11 CEST 2012

On Apr 29, 2012, at 20:23, "Richard O'Keefe" <> wrote:

> The question is not "how do we match an empty list" for which
> f([]) -> ... is as good as it gets, but
>>>> why use ?= in a guard and not =, and what does ?= mean outside a
>>>> guard?

You actually answered that quite well, and I understood your answer.  I was just trying to understand *why* or *when* binding in guards might be necessary.



More information about the eeps mailing list