Re: "cannot coerce inexact literal to fixnum"

Peter Bex <[email protected]> Sat, 10 Feb 2024 14:38:33 +0100
Newsgroups	gmane.lisp.scheme.chicken
Message-ID	<Zcd8WSki__qlpidQ@doggett>
On Sat, Feb 10, 2024 at 02:32:16PM +0200, Al wrote:
> That would be fine but where does that happen? csc actually barfs on my
> Scheme code (as per the subject line), instead of emitting C code to
> encode/decode into a string at runtime, as you mention.

That's because you're using fixnum mode.  As I explained, using literals
that might be too large for fixnums break the fixnum mode's premise that
everything must be a fixnum.

> It won't even let me use string->number by hand.

That's because string->number gets constant-folded and evaluated at
compile-time.

> The only thing that worked was
> 
> (cond-expand
>   (csi
>     (define  INT32_MAX  #x7fffffff)
>     (define  INT32_MIN #x-80000000)
>     (define UINT32_MAX  #xffffffff)
>     )
>   (else
>     ; chicken csc only does 31-bit literals in fixnum mode
>     (define INT32_MIN  (foreign-value "((int32_t)  0x80000000)" integer32))
>     (define INT32_MAX  (foreign-value "((int32_t)  0x7fffffff)" integer32))
>     (define UINT32_MAX (foreign-value "((uint32_t) 0xffffffff)"
> unsigned-integer32))
>     )
>   )

It would help if you tried to explain exactly _what_ you're trying to do
here, instead of _how_ you're trying to do it.  Why do you need these
constants?

> ... and I'm not sure what the implications of using a "foreign value"
> further down in my program are. If I assign them to another variable, does
> that variable also become a "foreign value"?

A foreign value is simply a value that gets calculated using the FFI.
The value itself, once calculated, won't be "special" in any way.  It's
just another fixnum.

> How about if I do (bitwise-and
> IMAX32 int)  to truncate a signed number to unsigned32 (which is what I'm
> actually using them for)?

Again, what are you trying to accomplish?

> > There's (currently) no option to force fixnum mode in a way that ignores
> > the existence 32-bit platforms.  Theoretically, it should be possible to
> > compile your code assuming fixnums (so it emits C integer literals) and
> > make it barf at compilation time if one tried to build for a 32-bit
> > platform using a #ifdef or something.  We just don't have the required
> > code to do this, and I'm not sure this is something we'd all want.
> 
> Well if csc emitted string->number code in fixnum mode when necessary, that
> would at least work.

It does that (more or less), as I explained.  And it *wouldn't* work,
because it can't make the assumption it won't be compiled on a system
that's 32 bits.

Cheers,
Peter
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