[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Making multiple values more consistent
- To: (BUG LISPM) at MIT-MC
- Subject: Re: Making multiple values more consistent
- From: MOON5@MIT-MC
- Date: Fri ,2 Jun 79 12:59:20 EDT
I would like to promote the following rule. If the result of a function
is used as an argument to a function, bound to a variable, or setq'ed
to a variable, only the first value of that function is used. If the result
of a function appears last in an explicit or implicit progn, and will
be the result of the containing form, then all values are propagated upward
to that containing (special) form. I think this will produce much more
Currently the interpreter does this for lambda-combinations and function
bodies, but I don't think it does it for other implicit progn's such as
cond clauses and exitvalues in new-style DO's.
The compiler does not currently do this. There are two cases: (1) the
result of the function will propagate up to be the result of the calling
function. The microcode can easily be changed to make this work by checking
for D-RETURN on the call, when an attempt is made to return multiple values.
This may take the place of indirect-ADI. (2) the result of the function
will be used by an internal multiple-value, multiple-value-list,
multiple-value-bind, etc. This probably requires some extension to the
compiler's destination mechanism to make work in all cases.
I don't think any of these changes will be hard to do.