Re: "cannot coerce inexact literal to fixnum"

[Al]

On 2024-02-10 13:00, Peter Bex wrote:

> These so-called "big-fixnums" are compiled into a string literal which gets 
> decoded on-the-fly at runtime into either a fixnum (on 64-bit) or a bignum (on 32-bit).


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


... 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"? 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)?


> 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. Although if I'm using fixnum mode, I'm 
probably looking for performance, and I'm not sure the subsequent C 
compiler is smart enough to optimize the "atoi" or whatever away into a 
constant. Maybe it is nowadays.


Otherwise, how do I write Scheme code to truncate a signed number to 
unsigned32? Resort to foreign values as I did above (or write foreign 
functions)?


-- Al