Use another language to call a function

This SO answer, by JJ Merelo, explained the difficulty on providing a simple solution. So this attempt takes the same approach as PicoLisp by summoning the interpreter at run time.

query.raku

#!/usr/bin/env raku

sub MAIN (Int :l(:len(:$length))) {
   my Str $String = "Here am I";
   $*OUT.print: $String if $String.codes ≤ $length
}

query.c

#include<stdio.h>
#include<stddef.h>
#include<string.h>

int Query(char *Data, size_t *Length) {
   FILE *fp;
   char buf[64];

   sprintf(buf, "/home/user/query.raku --len=%zu", *Length);
   if (!(fp = popen(buf, "r")))
      return 0;
   fgets(Data, *Length, fp);
   *Length = strlen(Data);
   return pclose(fp) >= 0 && *Length != 0;
}

Output:

gcc -Wall -o main main.c query.c
./main
Here am I