[Chicken-users] stream-filter

[Thomas Hafner]

Hello,

according to <http://srfi.schemers.org/srfi-40/srfi-40.html>
stream-filter should be used like this
  (stream-filter predicate? stream)
so I've tried that:

(require-extension srfi-40)
(define s0 (stream-delay (stream-cons "foo" stream-null)))
(define s1 (stream-filter (lambda x #t) s0))
(printf "~a\n" (stream-car s0))
(printf "~a\n" (stream-car s1))

Unfortunately but it fails. Without the last code line the output is
still ok:

|Version 2, Build 41 - linux-unix-gnu-x86-64 - [ 64bit dload ptables applyhook ]
|(c)2000-2006 Felix L. Winkelmann
|; loading ./filefind.scm ...
|; loading library posix ...
|; loading /usr/local/lib/chicken/1/srfi-40.scm ...
|; loading /usr/local/lib/chicken/1/srfi-40-base.so ...
|foo

But including the last code line something goes wrong:

|Version 2, Build 41 - linux-unix-gnu-x86-64 - [ 64bit dload ptables applyhook ]
|(c)2000-2006 Felix L. Winkelmann
|; loading ./filefind.scm ...
|; loading library posix ...
|; loading /usr/local/lib/chicken/1/srfi-40.scm ...
|; loading /usr/local/lib/chicken/1/srfi-40-base.so ...
|foo
|Error: (car) bad argument type: ()
|
|        Call history:
|
|        <eval>          (##sys#list (quote lambda) (quote ()) exp)
|        <eval>          (##srfi-40#make-stream (stream-low-level-lazy 
(stream-cons "foo" stream-null)))
|        <eval>          (vector (cons (quote suspension) (lambda () 
(stream-cons "foo" stream-null))))
|        <eval>          (cons (quote suspension) (lambda () (stream-cons "foo" 
stream-null)))
|        <eval>          (stream-filter (lambda x #t) s0)
|        <eval>          (printf "~a\n" (stream-car s0))
|        <eval>          (stream-car s0)
|        <eval>          (##srfi-40#make-stream (stream-low-level-delay (let 
((g0 stream-null)) (if (not (stream? g0)) (stream-error "attempt to...
|        <eval>          (vector (cons (quote suspension) (lambda () 
(stream-low-level-strict (let ((g0 stream-null)) (if (not (stream? g0)) 
(str......
|        <eval>          (cons (quote suspension) (lambda () 
(stream-low-level-strict (let ((g0 stream-null)) (if (not (stream? g0)) 
(stream-erro......
|        <eval>          (stream-low-level-strict (let ((g0 stream-null)) (if 
(not (stream? g0)) (stream-error "attempt to stream-cons onto non-...
|        <eval>          (not (stream? g0))
|        <eval>          (stream? g0)
|        <eval>          (cons "foo" g0)
|        <eval>          (printf "~a\n" (stream-car s1))
|        <eval>          (stream-car s1) <--

What's going on? What am I doing wrong?

I've installed eggs srfi-40 and stream-ext (v1.4.1). All is running on
Linux, kernel 2.6.15-23-amd64-k8 as distributed by Ubuntu.

Regards
  Thomas