| Date: Fri, 22 Sep 2006 10:29:31 -0400 (EDT)
| From: AndrevanTonder <andre_at_het.brown.edu>
|
| Actually, I agree with another poster that it would be nice if
| these expressions returned zero values instead of the current 1.
| In that case, maybe a "void" "type" would not be so far-fetched for
| such expressions (ignoring for the moment that the language is
| untyped).
|
| The reason I would like it if these expressions returned zero
| values is the following: I sometimes get hard-to-debug errors due
| to inconsistent data values containing #<unspecified>, due to
| obscure errors in logic, misplaced parentheses, etc. I can imagine
| that newcomers would run into this kind of error quite a bit more
| often.
|
| The problem with these errors is that they often occur long after
| the call that inserted the #<unspecified> value in the data
| structure. If these expressions returned no value, the error would
| occur immediately, as it really should, and one would not be able
| to build such inconsistent data values in the first place.
That is a good idea. This was not possible in R5RS because of
"Except for continuations created by the `call-with-values'
procedure, all continuations take exactly one value."
But R6RS 4.5 says:
"The continuations discarding these values accept any number of
values."
The language "value returned is unspecified" would be changed to
"returns no values"; there would be no object to name.
Received on Fri Sep 22 2006 - 12:02:42 UTC