GNU bug report logs - #58001
Cannot use 'read' in imported library

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Date: Thu, 22 Sep 2022 00:30:40 -0700
From: author@HIDDEN
Subject: Cannot use 'read' in imported library
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I'm using Guile version 3.0.5 from the Guix repository.

I've run into a strange issue with the read function from (scheme 
base). It cannot be used in an R7RS-style library. This only seems to 
apply to the read function. Other standard procedures work fine.

Let's say you have a library that uses read. Maybe it looks like this:

;; File: foo.scm
(define-library (foo)
  (import (scheme base))
  (export read-wrapped)
  (begin
    (define (read-wrapped port) (read port))))

Now, let's say you want to import that library somewhere else and use 
it's exported function read-wrapped:

;; File: main.scm
(import (scheme base))
(import (foo))
(display (read (current-input-port)))
(display (read-wrapped (current-input-port)))

If you try to run that main script (in the same directory as the foo 
library):

GUILE_LOAD_PATH=. guile --r7rs main.scm

You can enter get a datum for the first call to read, then you'll get 
an error for the second call:

foo.scm:1:0: In procedure read-wrapped:
Unbound variable: read

This only happens with read. If you replace read with a different 
standard procedure like boolean? then everything is fine (you'll see #f 
twice because the input port fails the predicate).

I'm pretty baffled. I've attached the dummy source files for 
convenience.


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<div id=3D"geary-body" dir=3D"auto"><div>I'm using Guile version 3.0.5 from=
 the Guix repository.<br><br>I've run into a strange issue with the <font f=
ace=3D"monospace">read</font> function from <font face=3D"monospace">(schem=
e base)</font>. It cannot be used in an R7RS-style library. This only seems=
 to apply to the <font face=3D"monospace">read</font> function. Other stand=
ard procedures work fine.<br><br>Let's say you have a library that uses <fo=
nt face=3D"monospace">read</font>. Maybe it looks like this:<br><br><div><f=
ont face=3D"monospace">;; File: foo.scm</font></div><div><font face=3D"mono=
space">(define-library (foo)</font></div><div><font face=3D"monospace">&nbs=
p; (import (scheme base))</font></div><div><font face=3D"monospace">&nbsp; =
(export read-wrapped)</font></div><div><font face=3D"monospace">&nbsp; (beg=
in</font></div><div><font face=3D"monospace">&nbsp; &nbsp; (define (read-wr=
apped port) (read port))))</font></div></div><div><br></div><div>Now, let's=
 say you want to import that library somewhere else and use it's exported f=
unction <font face=3D"monospace">read-wrapped</font>:</div><div><br></div><=
div><font face=3D"monospace">;; File: main.scm</font></div><div><div><font =
face=3D"monospace">(import (scheme base))</font></div><div><font face=3D"mo=
nospace">(import (foo))</font></div><div><font face=3D"monospace">(display =
(read (current-input-port)))</font></div><div><font face=3D"monospace">(dis=
play (read-wrapped (current-input-port)))</font></div></div><div><br></div>=
<div>If you try to run that <font face=3D"monospace">main</font> script (in=
 the same directory as the <font face=3D"monospace">foo</font> library):</d=
iv><div><br></div><div><font face=3D"monospace">GUILE_LOAD_PATH=3D. guile -=
-r7rs main.scm</font></div><div><br></div><div>You can enter get a datum fo=
r the first call to <font face=3D"monospace">read</font>, then you'll get a=
n error for the second call:</div><div><br></div><div><div><font face=3D"mo=
nospace">foo.scm:1:0: In procedure read-wrapped:</font></div><div><font fac=
e=3D"monospace">Unbound variable: read</font></div></div><div><br></div><di=
v>This only happens with <font face=3D"monospace">read</font>. If you repla=
ce <font face=3D"monospace">read</font> with a different standard procedure=
 like <font face=3D"monospace">boolean?</font> then everything is fine (you=
'll see <font face=3D"monospace">#f</font> twice because the input port fai=
ls the predicate).</div><div><br></div><div>I'm pretty baffled. I've attach=
ed the dummy source files for convenience.</div></div>
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