Re: Using '-1' in a method named '*'

[Andy Wingo]

Hi,

On Mon 27 Feb 2017 11:06, Alejandro Sanchez <address@hidden> writes:

> (define v (make <vector3> #:x 1))
>
> (* -1 v)  ; Does not work
> (* -2 v)  ; Works fine

I believe that Guile is doing strength reduction, transforming (* -1 v)
to (- 0 v).

It could be that this is totally the wrong thing.  Is (* x 2) -> (+ x x)
a valid transformation if you don't know the type of x?  I don't know.

I think there's currently an assumption that if you extend *, that you
will do so in a mathy way, and that you implement - + and similar.  But
in this case it's not the clear right thing to do.

WDYT?  We could remove this transformation, or only apply it when type
inference has run.

Andy