Common Lisp question

Okay, I feel like a dolt, but this is something that's always eluded me 
in CL. How do I write unicode (well, specifically multibyte) characters 
to a file?

For example:

(with-output-to-string (s)
(princ #\u+2022 s))

Error: Cannot write SIMPLE-CHAR into stream.

Makes sense. So...

(with-output-to-string (s nil :element-type 'character)
(princ #\u+2022 s))

"•"

Success. Let's try the same thing with a file, though:

(with-open-file (s #p"~/test.txt" :element-type 'character :direction 
:output)
(princ #\u+2022 s))

Error: Cannot write SIMPLE-CHAR into stream.

I've never been able to use with-open-file to create a "character" 
stream for any character class other than a base-char. How do I do this? :-)

Thanks!

Jeff M.

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Re: Common Lisp question

On Mon, Jul 21, 2014 at 12:21 AM, Jeffrey Massung <massung@gmail.com> wrote:

> Success. Let's try the same thing with a file, though:
>
> (with-open-file (s #p"~/test.txt" :element-type 'character :direction
> :output)
> (princ #\u+2022 s))
>
> Error: Cannot write SIMPLE-CHAR into stream.
>
> I've never been able to use with-open-file to create a "character" stream
> for any character class other than a base-char. How do I do this? :-)

You read the documentation of the CL function OPEN, supplemented by
the implementation specific details that the documentation for OPEN
directs you to look at.

(The documentation for WITH-OPEN-FILE directs you to OPEN.)

P.

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Re: Common Lisp question

Hi Jeff,

Have you tried setting this:

(lw:set-default-character-element-type 'lw:simple-char)


http://www.lispworks.com/documentation/lw61/LW/html/lw-966.htm


I set the default character element type in my .lispworks file and at the beginning of every delivery script.


Best,
Cam


On 21 Jul 2014, at 00:21, Jeffrey Massung <massung@gmail.com> wrote:

> 
> Okay, I feel like a dolt, but this is something that's always eluded me in CL. How do I write unicode (well, specifically multibyte) characters to a file?
> 
> For example:
> 
> (with-output-to-string (s)
> (princ #\u+2022 s))
> 
> Error: Cannot write SIMPLE-CHAR into stream.
> 
> Makes sense. So...
> 
> (with-output-to-string (s nil :element-type 'character)
> (princ #\u+2022 s))
> 
> "•"
> 
> Success. Let's try the same thing with a file, though:
> 
> (with-open-file (s #p"~/test.txt" :element-type 'character :direction :output)
> (princ #\u+2022 s))
> 
> Error: Cannot write SIMPLE-CHAR into stream.
> 
> I've never been able to use with-open-file to create a "character" stream for any character class other than a base-char. How do I do this? :-)
> 
> Thanks!
> 
> Jeff M.


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Re: Common Lisp question

On 20 Jul 2014, at 23:21, Jeffrey Massung <massung@gmail.com> wrote:

> 
> Success. Let's try the same thing with a file, though:
> 
> (with-open-file (s #p"~/test.txt" :element-type 'character :direction :output)
> (princ #\u+2022 s))

1. You need to set the external format for the file so LW knows how to encode the Unicode.  There is a mass of LW documentation on this, most of which I have not read, but :utf-8 will work as en external format.  There is almost certainly a way of making that be the default external format.

2. You then need to make sure that the characters you write can be encoded in that format, and (at least for LW) this means they need to be LW:SIMPLE-CHARs not CHARACTERs.  Camille mentioned how you can make this the default.

So:

(with-open-file (s #p"/tmp/ts.out" 
                   :element-type 'lw:simple-char
                   :external-format ':utf-8
                   :direction ':output
                   :if-exists ':supersede)
  (princ #\u+2022 s))

This is all described in the "Internationalization" chapter of the manual

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