Il giorno 18/mag/2015, alle ore 21.34, Jens Axel Søgaard ha scritto:
>
>
> 2015-05-18 21:25 GMT+02:00 Michael Tiedtke :
> Il giorno 18/mag/2015, alle ore 20.50, Jos Koot ha scritto:
>
> > I think Rackets's reference and guide are *very clear* about eq?, eqv? and
> > equal?.
>
> Yes, right. It
Il giorno 18/mag/2015, alle ore 22.25, Alexander D. Knauth ha scritto:
>
> On May 18, 2015, at 1:19 AM, Michael Tiedtke
> wrote:
>
>> I'm new to Racket but even R5RS is rather clear about this issue:
>>
>> (citation from doc/r5rs/r5rs-std/r5rs-Z-H-9.html)
>>> (eq? 2 2) ===> unspecified
>
On Mon, May 18, 2015 at 08:50:50PM +0200, Jos Koot wrote:
>
> At the mathematical level equality is a difficult and in many cases even an
> unsolvable thing.
Indeed. It is suspected by some that difficulties with equality lie at
the root of problems with set theory.
There are two concepts of eq
[mailto:michael.tied...@o2online.de]
Sent: lunes, 18 de mayo de 2015 21:26
To: Jos Koot; racket-users@googlegroups.com
Subject: Re: [racket-users] Strange behaviour of the eq? operator in racket
repl
snip
Maybe, I never thought about that in mathematical terms if not with the
concept
of identity. How could
On May 18, 2015, at 1:19 AM, Michael Tiedtke
wrote:
> I'm new to Racket but even R5RS is rather clear about this issue:
>
> (citation from doc/r5rs/r5rs-std/r5rs-Z-H-9.html)
>> (eq? 2 2) ===> unspecified
In Racket, (eq? 2 2) is specified as true.
It says here:
http://docs.racket-lang.org/
ery distinct kind of
equality.
Jos
-Original Message-
From: racket-users@googlegroups.com [mailto:racket-users@googlegroups.com]
On Behalf Of Greg Hendershott
Sent: lunes, 18 de mayo de 2015 20:56
To: racket-users@googlegroups.com
Subject: Re: [racket-users] Strange behaviour of the eq? operato
2015-05-18 21:25 GMT+02:00 Michael Tiedtke :
> Il giorno 18/mag/2015, alle ore 20.50, Jos Koot ha scritto:
>
> > I think Rackets's reference and guide are *very clear* about eq?, eqv?
> and
> > equal?.
>
> Yes, right. It was the Racket Reference to tell me exactly that eqv? is an
> eq? that
> work
Il giorno 18/mag/2015, alle ore 20.50, Jos Koot ha scritto:
> I think Rackets's reference and guide are *very clear* about eq?, eqv? and
> equal?.
Yes, right. It was the Racket Reference to tell me exactly that eqv? is an eq?
that
works for numbers and characters, too. I really had to look this
In my early time learning Racket, I wish someone had given me the
following advice:
"""
For now? Just use `equal?`.
`equal?` will usually do the right thing, including for numbers,
strings, symbols, immutable lists, and so on. A type-specific function
like `=` or `string-=?` might be a bit faster
cases even an
unsolvable thing.
Jos
-Original Message-
From: racket-users@googlegroups.com [mailto:racket-users@googlegroups.com]
On Behalf Of Michael Tiedtke
Sent: lunes, 18 de mayo de 2015 19:00
To: racket-users@googlegroups.com
Subject: Re: [racket-users] Strange behaviour of t
Il giorno 18/mag/2015, alle ore 18.06, Atticus ha scritto:
> I guess it's a matter of definition. I must admit that i didn't reflect
> on equality that much.
>
> My (very limited) knowledge about that stuff comes mostly from the "The
> Little Schemer" which imho explains it really well with the '
I guess it's a matter of definition. I must admit that i didn't reflect
on equality that much.
My (very limited) knowledge about that stuff comes mostly from the "The
Little Schemer" which imho explains it really well with the 'eqan?' and
'eqlist?' procedure.
The reason why i checked (eq? 'symbol
SICP isn' the bible, especially not on programming language knowledge. I'd
recommend checking out relevant literature instead.
On May 18, 2015, at 8:24 AM, Michael Tiedtke
wrote:
> Structure and Interpretation of Computer Programs (sicp2) about sameness:
>
> https://mitpress.mit.edu/
Structure and Interpretation of Computer Programs (sicp2) about sameness:
https://mitpress.mit.edu/sicp/full-text/book/book-Z-H-16.html#footnote_Temp_230
> We can consider two symbols to be ``the same'' if they consist of the same
> characters in the same order. Such a definition skirts a deep is
George Neuner writes:
> Hi,
>
> On 5/17/2015 5:32 PM, Atticus wrote:
>> ---
>> $ racket
>> Welcome to Racket v6.1.1.
>> > (eq? 'l 'l)
>> #f
>> > (eq? 'l 'l)
>> #t
>> >
>>
>> $ racket --no-jit
>> Welcome to Racket v6.1.1.
>> > (eq? 'l 'l)
>> #f
>> > (eq? 'l 'l)
>> #t
>> > (
Yes, Scheme (and therefore Racket) has eq?, eqv?, and equal?. I understand the
desire for eq? and equal?, but I’ve always been skeptical of the necessity of
eqv?. Either way, Scheme left this behavior unspecified, but I believe Racket
specifies it (though I could be wrong).
Racket has two kinds
I'm new to Racket but even R5RS is rather clear about this issue:
(citation from doc/r5rs/r5rs-std/r5rs-Z-H-9.html)
> (eq? 2 2) ===> unspecified
>
> Rationale: It will usually be possible to implement eq? much more
> efficiently than eqv?, for example, as a simple pointer comparison instead
Hi,
On 5/17/2015 5:32 PM, Atticus wrote:
---
$ racket
Welcome to Racket v6.1.1.
> (eq? 'l 'l)
#f
> (eq? 'l 'l)
#t
>
$ racket --no-jit
Welcome to Racket v6.1.1.
> (eq? 'l 'l)
#f
> (eq? 'l 'l)
#t
> (eq? 'l 'l)
#f
> (eq? 'l 'l)
#t
> (eq? 'l 'l)
#t
> (eq? 'l 'l)
#t
> (eq? 'l
Hello everyone,
So i am trying to learn scheme in my free time (unfortunately my
university doesn't use scheme in their undergraduate courses) and i was
comparing the equality operators in gambit and racket and encountered a
strange behaviour with the eq? operator in racket. To my surprise
compari
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