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Re: Comparison operators for strings /and/ numbers?
From: |
Arne Babenhauserheide |
Subject: |
Re: Comparison operators for strings /and/ numbers? |
Date: |
Thu, 24 Aug 2017 19:58:42 +0200 |
Ralf Mattes <address@hidden> 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
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