Warren writes: > In light of Simon's > proposal, the "(sic)" proposal should now be seen as a source of examples, > rather than a still viable proposal. As Simon notes, neither extended guards nor views subsumes the other. Views are as viable as they ever were. Roughly speaking, extended guards are helpful when dealing with an *expression* that may return *zero or one* values (which is why they sensibly tie to Maybe), while views are helpful when dealing with a *bound variable* that may take on *any number* of forms. It is possible a neat syntax exists for dealing with *expressions* that may take on *any number* of forms, and this would subsume both extended guards and views. Arguably, `case' expressions do just this! -- P ----------------------------------------------------------------------- Philip Wadler [EMAIL PROTECTED] Bell Laboratories http://cm.bell-labs.com/cm/cs/who/wadler/ Lucent Technologies office: +1 908 582 4004 700 Mountain Ave, Room 2T-304 fax: +1 908 582 5857 Murray Hill, NJ 07974-0636 USA home: +1 908 626 9252 -----------------------------------------------------------------------
