[Gauche-devel] Fwd: SRFI-60 integer->list and list->integer

[Sascha Z. <ce...@gm...>]

Gauche list->integer function does not check for negative numbers either:

gosh> (integer->list 0)
()
gosh> (integer->list -1)
()
gosh> (list->integer (integer->list -1))
0


---------- Forwarded message ----------
From: Aubrey Jaffer <ag...@al...>
Date: 2012/1/10
Subject: Re: SRFI-60 integer->list and list->integer
To: Sascha Ziemann <ce...@gm...>


 | Date: Tue, 10 Jan 2012 15:56:14 +0100
 | From: Sascha Ziemann <ce...@gm...>
 |
 | Hello,
 |
 | I have a question about the integer->list function in SRFI-60.
 |
 | The function list->integer does not seem to be the reverse function
 | for integer->list:
 |
 | $ scm
 | > (list->integer (integer->list -1))
 | 0
 |
 | Is this the intended behavior?

integer->list works only for non-negative numbers.

The prototype for the first argument, 'k' indicates a non-negative
number in the conventions for R4RS and R5RS.

 Function: integer->list k len
 Function: integer->list k
     integer->list returns a list of len booleans corresponding to
     integer->each bit of the given integer. #t is coded for each 1;
     integer->#f for 0. The len argument defaults to (integer-length
     integer->k).

SRFI-60 should have explicitly stated this restriction and the
implementation should signal an error for negative numbers.