Re: guile & r5rs

[Jim Blandy <jimb@red-bean.com>]

First off, let me make it clear that 1) I agree with you that it's
undesirable behavior, and 2) I've thought of a way to fix it that I
really like, so I will do that.

So now I can split hairs without people thinking I'm a jerk.  :)

I think it would be a mistake for R5RS to dictate the precision with
which inexact conversions like the ones we're discussing take place.
When looking at these problems, I just barely managed to come up with
solutions, using the frayed edges of floating-point support.  I can
imagine some cases where this simply won't be possible.

For example, both of the solutions I described involve doing the
computation in bignums, and then converting to double at the very end.
There may not be any other way to win.  I'm simply not going to bother
with that for the complex trig functions.  And I'll bet nobody else
has, either.

guile> (sin (expt 10 500))
+#.#

I think this is definitely, and deliberately, conforming behavior.