[m-dev.] Suggestion for a new "where" operator

Peter Schachte schachte at cs.mu.OZ.AU
Mon Aug 4 15:14:00 AEST 2003

> The idea is that an expression (E where G) denotes the expression E
> computed using the goal G.

Sounds like a great idea.

Suggestion:  make the precedence of 'where' higher (lower number) than
'=', so you could write

	f(X) = Y where ....

I think this is prettier than

	f(X) = Y :- ....

The only problem with this is syntactic:  people will tend to write

	X where p(X), q(X)

instead of

	X where (p(X), q(X))

and no doubt the error message they get will not immediately help them
realize the simple precedence problem.

Peter Schachte              If a nation values anything more than freedom, it
schachte at cs.mu.OZ.AU        will lose its freedom; and the irony of it is that
www.cs.mu.oz.au/~schachte/  if it is comfort or money that it values more, it
Phone: +61 3 8344 1338      will lose that too. -- Somerset Maugham 
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