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digitalmars.D.learn - Pure

reply "Ola Fosheim =?UTF-8?B?R3LDuHN0YWQi?= writes:
Is pure meant to be a compiler hint so that it is up to the 
programmer to enforce it? It is sometimes useful to maintain 
hidden state for lazy evaluation, that does not affect purity 
optimizations:

e.g.

a = foo(1) // evaluates, caches and returns value
b = foo(1) // returns cached value
c = foo (1) // returns cached value

is optimized to

a = b = c = foo(1) // evaluates, caches and returns value
Jan 08 2014
next sibling parent "bearophile" <bearophileHUGS lycos.com> writes:
Ola Fosheim Grøstad:


 Is pure meant to be a compiler hint so that it is up to the 
 programmer to enforce it?


Nope, it's enforced by the compiler. (But its rules are not 
immediately obvious, there are three kinds of purity, strong, 
weak and constant purity, etc). There are several corners cases, 
etc.

Bye,
bearophole
Jan 08 2014
prev sibling parent reply "John Colvin" <john.loughran.colvin gmail.com> writes:
On Wednesday, 8 January 2014 at 18:40:46 UTC, Ola Fosheim Grøstad 
wrote:

 Is pure meant to be a compiler hint so that it is up to the 
 programmer to enforce it? It is sometimes useful to maintain 
 hidden state for lazy evaluation, that does not affect purity 
 optimizations:

 e.g.

 a = foo(1) // evaluates, caches and returns value
 b = foo(1) // returns cached value
 c = foo (1) // returns cached value

 is optimized to

 a = b = c = foo(1) // evaluates, caches and returns value


pure is enforced by the compiler (bugs allowing...). However, D 
purity has more shades to it than the black and white concept 
that most are familiar with.

I'll leave it to someone who knows better to explain it.
Jan 08 2014
parent reply "Paolo Invernizzi" <paolo.invernizzi gmail.com> writes:
On Wednesday, 8 January 2014 at 19:04:24 UTC, John Colvin wrote:

 On Wednesday, 8 January 2014 at 18:40:46 UTC, Ola Fosheim 
 Grøstad wrote:

 Is pure meant to be a compiler hint so that it is up to the 
 programmer to enforce it? It is sometimes useful to maintain 
 hidden state for lazy evaluation, that does not affect purity 
 optimizations:


 pure is enforced by the compiler (bugs allowing...). However, D 
 purity has more shades to it than the black and white concept 
 that most are familiar with.

 I'll leave it to someone who knows better to explain it.


This one is a good introduction, or at least the best one I can 
remember:

http://klickverbot.at/blog/2012/05/purity-in-d/

Very well written, a pleasure to read.

/Paolo
Jan 08 2014
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 01/08/2014 11:09 AM, Paolo Invernizzi wrote:


 This one is a good introduction, or at least the best one I can remember:

 http://klickverbot.at/blog/2012/05/purity-in-d/

 Very well written, a pleasure to read.


And very hard to translate! :) In case a Turkish reader is interested, 
here is the translation:

   http://ddili.org/makale/saflik.html

Ali
Jan 08 2014
next sibling parent reply "Ola Fosheim =?UTF-8?B?R3LDuHN0YWQi?= writes:
On Wednesday, 8 January 2014 at 19:26:28 UTC, Ali Çehreli wrote:

 And very hard to translate! :) In case a Turkish reader is 
 interested, here is the translation:

   http://ddili.org/makale/saflik.html



So, "saflik" is "pure" in turkish, cool! I like the sound of it. 
8-D
Jan 08 2014
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 01/08/2014 11:39 AM, "Ola Fosheim Grøstad" 
<ola.fosheim.grostad+dlang gmail.com>" wrote:> On Wednesday, 8 January 
2014 at 19:26:28 UTC, Ali Çehreli wrote:

 And very hard to translate! :) In case a Turkish reader is interested,
 here is the translation:

   http://ddili.org/makale/saflik.html



 So, "saflik" is "pure" in turkish, cool! I like the sound of it. 8-D


It is never easy, is it? :)

The reason it is "saflik" in the URL is because file names better be in 
ASCII due to different capabilities of different file systems. The word 
is actually "saflık". saf means pure and saflık means "purity". The 
vowel ı does not appear in English: It is close to the sound made just 
before the 'n' in "action" but not exactly the same.

Ali
Jan 08 2014
parent "Ola Fosheim =?UTF-8?B?R3LDuHN0YWQi?= writes:
On Wednesday, 8 January 2014 at 21:37:24 UTC, Ali Çehreli wrote:

 On 01/08/2014 11:39 AM, "Ola Fosheim Grøstad"

 So, "saflik" is "pure" in turkish, cool! I like the sound of


 it. 8-D

 It is never easy, is it? :)

 The reason it is "saflik" in the URL is because file names 
 better be in ASCII due to different capabilities of different 
 file systems. The word is actually "saflık". saf means pure and 
 saflık means "purity". The vowel ı does not appear in English: 
 It is close to the sound made just before the 'n' in "action" 
 but not exactly the same.


I am trying very hard to put the "action" phoneme into "saflık", 
not sure if I got it irght, but I still like the sound of it! :-)

And thanks to the list members that put some light on the 
diversity of "pure" in D, for me.
Jan 09 2014
prev sibling parent reply John Carter <john.carter taitradio.com> writes:
 Very well written, a pleasure to read.





 And very hard to translate! :)


Leaping off the immediate topic of computer language D into the realm
of human languages English and Turkish...

With the Sapir–Whorf hypothesis in the back of my mind...

What makes it harder to translate?

Is there a human language in which these concepts would be more easily
discussed?

I was always fascinated by early translations (1980 and before era) of
Japanese machine manuals... It was tempting to find the
mistranslations funny, until I realised...

* You could never remember the words. Your memory is fundamentally
governed by the language you speak. Thus when you try remember (and
relate to a colleague) a subtly garbled chunk of that language, your
brain autocorrects it and refuses to reproduce the mistakes!

* The differences indicated curious and subtle differences in thought
processes of the original authors and translators. Not better or worse
processes. Different. Interesting. Subtle.

* The categories of mistakes made by, say German German to English
translators, were very different.

So I have always been fascinated by Sapir-Whorf, but it seems to be
very subtle and nuanced and unexpected in practical effect.


On Thu, Jan 9, 2014 at 8:26 AM, Ali Çehreli <acehreli yahoo.com> wrote:

 On 01/08/2014 11:09 AM, Paolo Invernizzi wrote:


 This one is a good introduction, or at least the best one I can remember:

 http://klickverbot.at/blog/2012/05/purity-in-d/

 Very well written, a pleasure to read.


 And very hard to translate! :) In case a Turkish reader is interested, here
 is the translation:

   http://ddili.org/makale/saflik.html

 Ali




-- 
John Carter
Phone : (64)(3) 358 6639
Tait Electronics
PO Box 1645 Christchurch
New Zealand

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Jan 08 2014
next sibling parent =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 01/08/2014 12:20 PM, John Carter wrote:


 Very well written, a pleasure to read.





 And very hard to translate! :)


 Leaping off the immediate topic of computer language D into the realm
 of human languages English and Turkish...

 With the Sapir–Whorf hypothesis in the back of my mind...

 What makes it harder to translate?


What made is harder to translate was myself because I found some of the 
sentences in the original article more complicated than my little mind 
could handle. :)

I find languages fascinating myself. Agreeing with everything you said, 
merely the innateness of the whole thing and the way languages mutate on 
their own is sufficient fascination for me.

Ali
Jan 08 2014
prev sibling parent "Meta" <jared771 gmail.com> writes:
On Wednesday, 8 January 2014 at 20:21:22 UTC, John Carter wrote:

 Very well written, a pleasure to read.





 And very hard to translate! :)


 Leaping off the immediate topic of computer language D into the 
 realm
 of human languages English and Turkish...

 With the Sapir–Whorf hypothesis in the back of my mind...

 What makes it harder to translate?

 Is there a human language in which these concepts would be more 
 easily
 discussed?

 I was always fascinated by early translations (1980 and before 
 era) of
 Japanese machine manuals... It was tempting to find the
 mistranslations funny, until I realised...

 * You could never remember the words. Your memory is 
 fundamentally
 governed by the language you speak. Thus when you try remember 
 (and
 relate to a colleague) a subtly garbled chunk of that language, 
 your
 brain autocorrects it and refuses to reproduce the mistakes!

 * The differences indicated curious and subtle differences in 
 thought
 processes of the original authors and translators. Not better 
 or worse
 processes. Different. Interesting. Subtle.

 * The categories of mistakes made by, say German German to 
 English
 translators, were very different.

 So I have always been fascinated by Sapir-Whorf, but it seems 
 to be
 very subtle and nuanced and unexpected in practical effect.


 On Thu, Jan 9, 2014 at 8:26 AM, Ali Çehreli 
 <acehreli yahoo.com> wrote:

 On 01/08/2014 11:09 AM, Paolo Invernizzi wrote:


 This one is a good introduction, or at least the best one I 
 can remember:

 http://klickverbot.at/blog/2012/05/purity-in-d/

 Very well written, a pleasure to read.


 And very hard to translate! :) In case a Turkish reader is 
 interested, here
 is the translation:

   http://ddili.org/makale/saflik.html

 Ali




On a small tangent, I believe the Sapir-Whorf thesis has been 
disproved. However, I definitely think there might be a similar 
effect of programming languages on programmers.
Jan 09 2014