eaker@sunbelt.crd.ge.com (Charles E Eaker) (03/12/91)
In casting about for "Forth-like" names for interpreted counterparts to
IF, ELSE, and THEN, the candidates [IF] .IF and #IF (etc.) have been
offered and commented on. Here's my two cents.
I don't like .IF because it conflicts with the traditional use of the
period to mean "print".
I don't like [IF] because it puts the brackets in what will sometimes
be the wrong place. In a definition one would have to use
[ condition [IF] ]
to do a run-time check to see what should be compiled, and the brackets
around the IF strike me as redundant or misleading. Furthermore,
brackets are not uniformly used in Forth to mark an immediate word (nor
should they be).
#IF is ok with me. When tens of thousands of programmers look at it for
the first time, their gut reaction will be nearly correct. I don't mind
porting C-isms to Forth as long as they aren't contrary to Forth
custom. This usage of '#' doesn't conflict with its traditional one.
A Forth-like set of names for conditional compilation would take
advantage of a strong Forth association that is similar to the function
of the proposed words. Since the proposed functions are basically those
of skipping words in the input stream, we probably ought to pick
something that uses parentheses, especially since we all know that ( is immediate. (Oops, maybe it should have been named [(] :-) )
The following works for me:
: new-word
[ condition ]
IF(
words-to-compile-or-interpret-if-condition-is-true
)ELSE(
words-to-compile-or-interpret-if-condition-is-false
)THEN
words-to-compile-or-interpret-no-matter-what
;
A disadvantage (perhaps a serious one) is that C (and FORTRAN)
programmers coming to Forth are likely to completely misinterpret
IF( ... )THEN. But, I submit, this proposal is "Forthy".
Chuck Eaker / P.O. Box 8, K-1 3C12 / Schenectady, NY 12301 USA
eaker@crd.ge.com eaker@crdgw1.UUCP (518) 387-5964
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Chuck Eaker / P.O. Box 8, K-1 3C12 / Schenectady, NY 12301 USA
eaker@crd.ge.com eaker@crdgw1.UUCP (518) 387-5964