How can I read a single line of text that is longer than 1023 characters?

[shogo314]

The std/os/readline function only reads up to 1023 characters. How can I read a longer line of text?

[TimWhiting]

You can keep reading (call the function again), but I guess the more specific question you'd have is knowing whether you've read all the stdin / line yet right, since there is no flag letting you know if it read a full line.

For now you can create your own c function that does what you want, and link to it from Koka: Here is all the definitions from std/os/readline.kk, std/os/readline-inline.c, and the kklib c library os.c where this all is implemented.

Extern imports, extern functions etc, are not limited to the std core libraries. You can use them in your code. (kklib.h and all of the imports / types defined in your module are defined prior to your c file is spliced in, so you shouldn't have to worry about c includes).

extern import
  c file "readline-inline.c"
  
pub fun readline() : <console,exn> string
  match readline-err() 
    Error(exn)  -> Error(exn.prepend("unable to read from stdin")).untry
    Ok(line)    -> line

extern readline-err() : console error<string>
  c "kk_os_read_line_error"  
  js "sync_readline_err"

static kk_std_core_exn__error kk_os_read_line_error( kk_context_t* ctx ) {
  kk_string_t content;
  const int err = kk_os_read_line(&content,ctx);
  if (err != 0) return kk_error_from_errno(err,ctx);
           else return kk_error_ok(kk_string_box(content),ctx);
}

kk_decl_export int kk_os_read_line(kk_string_t* result, kk_context_t* ctx)
{
  char buf[1024];
  if (fgets(buf, 1023, stdin) == NULL) return errno;
  buf[1023] = 0;      // ensure zero termination
  const size_t len = strlen(buf);
  if (len > 0 && buf[len-1] == '\n') {
    buf[len-1] = 0;   // remove possible ending newline character
  }
  *result = kk_string_alloc_from_qutf8(buf, ctx);
  return 0;
}