Re: Comparison operators for strings /and/ numbers?

[Arne Babenhauserheide <arne_bab@web.de>]

[-- Attachment #1: Type: text/plain, Size: 1059 bytes --]


Ralf Mattes <rm@seid-online.de> writes:

> On Thu, Aug 24, 2017 at 10:29:41AM +0200, Arne Babenhauserheide wrote:
>> Hi Christopher,
>> 
>> You can use GOOPS to make them generic:
>> 
>> > (import (oop goops))
>> > (< "a" "b")
>
> That's not what David suggested.

No, it is not. I wrote my reply before I saw his.

>> <unnamed port>:3:0: <unnamed port>:3:0: In procedure <: Wrong type argument in position 1: "a"
>> 
>> Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
>> [1]> (define-method (< (a <string>) (b <string>)) (string<? a b))
>> [1]> (< "a" "b")
>> $1 = #t
>> 
>> For some functions you might need to call (define-generic <function>)
>> before this (you’ll notice because define-method will signal an error).
>
> Is that still the case?

Yes. Try:

> (import (oop goops))
> (define-method (list (a <string>)))
ERROR: In procedure scm-error:
ERROR: #<procedure list _> is not a valid generic function

Best wishes,
Arne
-- 
Unpolitisch sein
heißt politisch sein
ohne es zu merken

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]