Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Neil Girdhar]

I prefer Python's syntax.  

In the Keras example, Python pays off compared to the XML or YAML or 
whatever as soon as you need to define something programmatically.  For 
example, if your model is generated based on some other input.  

Anyway, most of your time is not spent typing punctuation.  Most of your 
time is spent debugging.

I wish that LaTeX, the DSLs I use, were implemented as a Python package.  
There are a thousand terrible design decision in latex that could all be 
fixed if it had been done as one good Python package.  Maybe LuaTex will 
end up fullfilling the dream.

On Thursday, August 30, 2018 at 9:41:46 PM UTC-4, Guido van Rossum wrote:
>
> On Fri, Aug 31, 2018 at 3:19 AM, Michael Selik  > wrote:
>
>> On Thu, Aug 30, 2018 at 5:31 PM James Lu > 
>> wrote:
>>
>>> It would be nice if there was a DSL for describing neural networks 
>>> (Keras).
>>>
>>> model.add(Dense(units=64, activation='relu', input_dim=100))
>>> model.add(Dense(units=10, activation='softmax'))
>>>
>>>
>> Why not JSON or XML for cross-language compatibility?
>>
>
> Presumably because those are even harder to read and write for humans.
>
> I believe that the key issue with using Python as a DSL has to do with its 
> insistence on punctuation -- the above example uses nested parentheses, 
> commas, equal signs, and quotation marks. Those are in general needed to 
> avoid ambiguities, but DSLs are often highly stylized, and a language that 
> doesn't need them has a certain advantage. For example if a shell-like 
> language was adopted, the above could probably be written with spaces 
> instead of commas, parentheses and equal signs, and dropping the quotes 
> (though perhaps it would be more readable if the equal signs were kept).
>
> I'm not sure how we would go about this though. IIRC there was a proposal 
> once to allow top-level function calls to be written without parentheses, 
> but it was too hard to make it unambiguous (e.g. would "foo +1" mean 
> "foo(+1)" or "foo + 1"?)
>
> -- 
> --Guido van Rossum (python.org/~guido)
>
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Abdur-Rahmaan Janhangeer]

wrote a quick article here :

https://www.pythonmembers.club/2018/09/03/how-to-create-your-own-dsldomain-specific-language-in-python/
-- 
Abdur-Rahmaan Janhangeer
https://github.com/abdur-rahmaanj
Mauritius
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Stefan Behnel]

Matthew Einhorn schrieb am 31.08.2018 um 20:57:
> with model:
> with Dense():
> units = 64
> activation = 'relu'
> input_dim = 100
> 
> with Dense():
> units = 10
> activation = 'softmax'

This looks like it could use 'class' instead of 'with'.

Stefan

___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Matthew Einhorn]

On Thu, Aug 30, 2018 at 8:31 PM James Lu  wrote:

> Why shouldn't Python be better at implementing Domain Specific Languages?
>
> [snip]
>
> It would be nice if there was a DSL for describing neural networks (Keras).
> The current syntax looks like this:
>
> model.add(Dense(units=64, activation='relu', input_dim=100))
> model.add(Dense(units=10, activation='softmax'))
>
>
How about something like this?

with model:
with Dense() as dense:
dense.units = 64
dense.activation = 'relu'
dense.input_dim = 100

with Dense() as dense:
dense.units = 10
dense.activation = 'softmax'

The `with` creates a context to which subsequent layers are added when
created within the context.

But it does suffer from the fact that the `with` object's (or the
underlying stack that would implement
this in the model/layers) scope is not local to the function, so if within
the `with` context you call a
function that creates a layer, the layer will be added to the caller's
context, which would be surprising.

I was working on a similar approach for a python GUI, and `with` seemed
like a very nice candidate,
but ran into this issue, which didn't seem to have a clean fix.

I also thought about using an decorator that pre-processes the AST for a
GUI description, which for
your example would look like something like:

with model:
with Dense():
units = 64
activation = 'relu'
input_dim = 100

with Dense():
units = 10
activation = 'softmax'

But here the issues are (a) the similarity with local variables may be
confusing (b) you'd need to
either make all `with` statements special, or annotate the `with`
statements that are going to be
processed by the compiler (e.g. by prefixing the object with a dash). It
seemed messy
enough that I'm still pondering this.

Matt
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Abdur-Rahmaan Janhangeer]

the implementation is very easy just a program and some ifs

if you need more complex, just some reading on tokens etc
but the first choice is enough

if in py competitions people are solving regex like questions and word
extractions without knowing they are solving compiler theory problems,
implementing DSL is very easy

Abdur-Rahmaan Janhangeer
https://github.com/Abdur-rahmaanJ
Mauritius
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Steven D'Aprano]

On Fri, Aug 31, 2018 at 11:39:16AM -0400, James Lu wrote:

> We should all take a look at Ruby Blocks and think about how Python 
> could benefit from something similar.

You are not the first person to suggest Ruby-like anonymous blocks or 
multi-statement lambdas.

https://duckduckgo.com/?q=python-ideas+ruby+blocks

Its not enough to just think about the benefits. We also need to think 
about the costs, the disadvantages, the possible syntax, and how well it 
fits into the existing language.

If anyone has some new and interesting ideas, that would be fantastic. 
But if we're just going to rehash the same rejected ideas again, please 
don't. Python is 20+ years old and the idea of multi-statement anonymous 
functions has been discussed since before Ruby even existed.


-- 
Steve
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Steven D'Aprano]

On Fri, Aug 31, 2018 at 11:14:35AM +0400, Abdur-Rahmaan Janhangeer wrote:

> let me take an example :
> 
> a DSL to calculate the cost of houses
[...]
> --- file ---
> house num 1,000
> house price 250,000
> calculate sum
> 
> --- output ---
> $ 250 000 000

I don't think the problem is people coming up with DSLs for their 
problems, but implementing those DSLs. Writing an informal specification 
is easy; writing the implementation is trickier.

For the above, you need an interpreter for the DSL, otherwise it is 
just a static data file that generates no output at all.



-- 
Steve
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[James Lu]

We should all take a look at Ruby Blocks and think about how Python could 
benefit from something similar.

> On Aug 31, 2018, at 3:14 AM, Abdur-Rahmaan Janhangeer  
> wrote:
> 
> i believe a DSL is simple enough for an enthusiastic py programmer to write 
> if you really wanted one
> 
> just write the tasks you need to accomplish, the data needed, the constrcuts 
> needed (if needed), the feel/look of it on your editor
> 
> plan first, come up with a good mock, then implement it. implementation is 
> easy, ideas are hard. good ideas offload the efforts on the implementation 
> side, they can also save you future troubles
> 
> let me take an example :
> 
> a DSL to calculate the cost of houses
> 
> aim : calculate cost of houses
> 
> input :
> num of houses
> price of house
> 
> output :
> price of houses
> 
> technical tasks :
> show to screen
> 
> it might go on like that
> 
> --- file ---
> 
> house num 1,000
> house price 250,000
> calculate sum
> 
> --- output ---
> 
> $ 250 000 000
> 
> in the above example, assumptions were made and functions crammed but you 
> have a dsl. real-life dsls are not far from the specs of this one but differ 
> in the tools used
> 
> Abdur-Rahmaan Janhangeer
> https://github.com/Abdur-rahmaanJ
> Mauritius
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Abdur-Rahmaan Janhangeer]

as for elm, you have to look twice not to see the python of it

Abdur-Rahmaan Janhangeer
https://github.com/Abdur-rahmaanJ
Mauritius
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Jeff Allen]

The word "domain" appears in this sense on the first page of Aho and 
Ullman and ANTLR (which I know you've used) describes itself as a tool 
for building domain-specific languages. Both pre-date Ruby I'm fairly sure.


James Lu, quoting Jonathan Fine, used the term "internal DSL" and 
although that's new to me, people seem to be interpreting it in the 
sense that Gradle is a Groovy DSL (note caps), a build tool a lot of 
software developers will be familiar with. In that case, what you write 
really is Groovy, but the execution environment has been pre-conditioned 
with objects and libraries that (almost) make a new language. When you 
understand what's going on (not sure I always do), it becomes possible 
to mix Gradle statements and Groovy freely. The most immediate benefit 
is that all the apparatus of expressions and types/methods is already 
present. So "internal" is the key word.


The point about punctuation is spot-on, I think: Groovy is relatively 
free of (makes optional) some punctuation, including the parentheses 
that make calls easily identifiable in Python. So quite possibly 
starting from Python is limiting if what you want is an*internal* DSL 
with a grammar you choose: the object system is fantastic-plastic, but 
the grammar is not. DSLs embedded in Python are common, of course 
(f-strings, regexes, SQL), and DSLs can generate Python from fragments 
with almost no constraints on their own grammar. iPython strikes me as 
possibly a Python internal DSL, or Django, but what they've done does 
not take us far from pure Python.


Jeff Allen

On 31/08/2018 05:07, Guido van Rossum wrote:


Hm. YAML is indeed a great, readable alternative to JSON or XML. But 
the term DSL implies (to me) more than just nested key-value pairs. 
(Though who knows maybe that's all Keras needs, and then it's a poor 
argument for having a DSL.)


Then again maybe I'm confusing DSL (which appears to be a Rubyism) 
with "little language": http://wiki.c2.com/?LittleLanguage


--
--Guido van Rossum (python.org/~guido )



___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Jonathan Fine]

James Lu started this thread by quoting me. Thank you, James, for the
compliment. And I feel somewhat obliged to contribute here, are at
removed I started the thread.

In the message James quoted, I also said


But most strengths, in another situation, can be a weakness. Language
design is often a compromise between conciseness and readability, ease
of use and performance, good for beginners and good for experts, and
many other factors. Such as innovation and stability.

Guido's decisions, as BDFL, have shaped Python and its community into
what it is now. It is one set of compromises. Other languages, such as
Ruby, have made different compromises. Now that the BDFL is on
vacation, the challenge is to maintain the essence of Python while
continuing to innovate.


It's important, of course, for the developers of a DSL to understand
the domain. I'm starting to learn http://elm-lang.org/. It describes
itself as

> A delightful language for reliable webapps.
> Generate JavaScript with great performance and no runtime exceptions.

The Elm developers have learnt a great deal from Python, and I think
that we in turn can learn from them. Particularly about catching
coding errors early, with good feedback. But that's a different
thread.

So I'd say to focus on improving the API to an existing library is a
good way to develop our understanding of DSLs more generally. James
provided a Keras example

model.add(Dense(units=64, activation='relu', input_dim=100))
model.add(Dense(units=10, activation='softmax'))

What might be better here, if allowed, is

model.extend([
Dense(units=64, activation='relu', input_dim=100),
Dense(units=10, activation='softmax'),
])

Another approach would be to provide a fluent interface.

https://martinfowler.com/bliki/FluentInterface.html
https://en.wikipedia.org/wiki/Fluent_interface

Done this want, we might get something like jQuery

   (
model
.dense(units=64, activation='relu', input_dim=100)
.dense(units=10, activation='softmax')
   )

JSON and XML and YAML have already been mentioned. Here's another,
XML-ish approach.

A combined list-dictionary is quite common. It's used widely in XML
(and SGML before it). So how to create such. A few years ago I
experimented with an API such as

 A(a=1, b=2)[
 X(1, 2, 3),
  Y[ ],
  ]

As I recall, someone told me that https://kivy.org does something
similar. Kivi and Elm, are systems I'd like to learn. Ease of use is
important in language and library design. We can learn from the
success of others, as well as from our own successes and failures
(smile).

-- 
Jonathan
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Paul Moore]

On Fri, 31 Aug 2018 at 06:36, Steven D'Aprano  wrote:

> Please no, Ruby has that, and the meaning of expressions depends on
> whether you put whitespace around operators or not.
>
> Given:
>
> def a(x=4)
> x+2
> end
> b = 1
>
> the result of "a+b" depends on the spaces around the plus sign:
>
> irb(main):005:0> a + b
> => 7
> irb(main):006:0> a +b
> => 3

Ewww. And people complain about *python's* use of significant whitespace???!?!!

Paul
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Abdur-Rahmaan Janhangeer]

i believe a DSL is simple enough for an enthusiastic py programmer to write
if you really wanted one

just write the tasks you need to accomplish, the data needed, the
constrcuts needed (if needed), the feel/look of it on your editor

plan first, come up with a good mock, then implement it. implementation is
easy, ideas are hard. good ideas offload the efforts on the implementation
side, they can also save you future troubles

let me take an example :

a DSL to calculate the cost of houses

aim : calculate cost of houses

input :
num of houses
price of house

output :
price of houses

technical tasks :
show to screen

it might go on like that

--- file ---

house num 1,000
house price 250,000
calculate sum

--- output ---

$ 250 000 000

in the above example, assumptions were made and functions crammed but you
have a dsl. real-life dsls are not far from the specs of this one but
differ in the tools used

Abdur-Rahmaan Janhangeer
https://github.com/Abdur-rahmaanJ
Mauritius
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Michael Selik]

On Thu, Aug 30, 2018, 9:23 PM David Mertz  wrote:

> On Fri, Aug 31, 2018, 12:08 AM Guido van Rossum  wrote:
>
>> Hm. YAML is indeed a great, readable alternative to JSON or XML. But the
>> term DSL implies (to me) more than just nested key-value pairs. (Though who
>> knows maybe that's all Keras needs, and then it's a poor argument for
>> having a DSL.)
>>
>
> Keras is deliberately very declarative in defining models. So indeed
> sequences and mappings and scalars is everything it needs. Maybe I'll
> actually implement the idea I sketch out in a small independent library.
>

Defining Keras models reminds me of the ugly ASP code I'd sometimes write
to create HTML in an object-oriented fashion. Writing plain HTML was
usually more pleasant and readable.

I suggested XML with that memory in mind. It's cumbersome for many tasks,
but Keras models in particular might be a good fit. Or YAML.

>
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Steven D'Aprano]

On Fri, Aug 31, 2018 at 03:40:22AM +0200, Guido van Rossum wrote:
> On Fri, Aug 31, 2018 at 3:19 AM, Michael Selik  wrote:
> 
> > On Thu, Aug 30, 2018 at 5:31 PM James Lu  wrote:
> >

[James]
> >> It would be nice if there was a DSL for describing neural networks
> >> (Keras).
> >>
> >> model.add(Dense(units=64, activation='relu', input_dim=100))
> >> model.add(Dense(units=10, activation='softmax'))

Is there something wrong with that style?

I'm not sure what syntax you would consider an improvement.


[Michael]
> > Why not JSON or XML for cross-language compatibility?

James dodn't mention cross-language compatibility, he presumably wants a 
better way to write machine learning code. Being able to exchange data 
from one application to another is great. Having to write your code as 
XML is not.


[Guido]
> Presumably because those are even harder to read and write for humans.

Indeed. One criticism of XML is that it is the hammer which leads people 
to treat every problem as a nail. "Just use XML". Now you have two 
problems *wink*


> I believe that the key issue with using Python as a DSL has to do with its
> insistence on punctuation -- the above example uses nested parentheses,
> commas, equal signs, and quotation marks. Those are in general needed to
> avoid ambiguities, but DSLs are often highly stylized, and a language that
> doesn't need them has a certain advantage.

Right -- especially for imperative-style code.

I'm reminded of an example from Leo Brodie's classic "Learning Forth", 
the top level application in an embedded washing machine controller:

WASH SPIN RINSE SPIN

That sort of punctuation-free imperative code elegantly matches the way 
we might right it down as a list of commands.


> For example if a shell-like
> language was adopted, the above could probably be written with spaces
> instead of commas, parentheses and equal signs, and dropping the quotes
> (though perhaps it would be more readable if the equal signs were kept).
> 
> I'm not sure how we would go about this though. IIRC there was a proposal
> once to allow top-level function calls to be written without parentheses,
> but it was too hard to make it unambiguous (e.g. would "foo +1" mean
> "foo(+1)" or "foo + 1"?)

Please no, Ruby has that, and the meaning of expressions depends on 
whether you put whitespace around operators or not.

Given:

def a(x=4)
x+2
end
b = 1

the result of "a+b" depends on the spaces around the plus sign:

irb(main):005:0> a + b
=> 7
irb(main):006:0> a +b
=> 3




-- 
Steve
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[David Mertz]

On Fri, Aug 31, 2018, 12:08 AM Guido van Rossum  wrote:

> Hm. YAML is indeed a great, readable alternative to JSON or XML. But the
> term DSL implies (to me) more than just nested key-value pairs. (Though who
> knows maybe that's all Keras needs, and then it's a poor argument for
> having a DSL.)
>

Keras is deliberately very declarative in defining models. So indeed
sequences and mappings and scalars is everything it needs. Maybe I'll
actually implement the idea I sketch out in a small independent library.

Then again maybe I'm confusing DSL (which appears to be a Rubyism) with
> "little language": http://wiki.c2.com/?LittleLanguage
>

I'm pretty sure I heard "DSL" before Ruby existed. Definitely before Ruby
entered my consciousness as another neat language.  I don't really care
whether a DSL needs to be Turing complete, but I think many such are used
primary declaratively. Mostly though I was pointing out that Keras doesn't
need flow and branching for it's model definitions.
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Guido van Rossum]

On Fri, Aug 31, 2018 at 4:04 AM, David Mertz  wrote:

> On Thu, Aug 30, 2018 at 9:41 PM Guido van Rossum  wrote:
>
>> On Fri, Aug 31, 2018 at 3:19 AM, Michael Selik  wrote:
>>
>>> On Thu, Aug 30, 2018 at 5:31 PM James Lu  wrote:
>>>
 It would be nice if there was a DSL for describing neural networks
 (Keras).

 model.add(Dense(units=64, activation='relu', input_dim=100))
 model.add(Dense(units=10, activation='softmax'))


>>> Why not JSON or XML for cross-language compatibility?
>>>
>>
>> Presumably because those are even harder to read and write for humans.
>>
>
> Guido is absolutely right (as usual) that JSON or XML would be *vastly*
> harder to read than that very clean Python code.
>
> That said, if you wanted a "DSL", the perfect choice would be YAML.
>

Hm. YAML is indeed a great, readable alternative to JSON or XML. But the
term DSL implies (to me) more than just nested key-value pairs. (Though who
knows maybe that's all Keras needs, and then it's a poor argument for
having a DSL.)

Then again maybe I'm confusing DSL (which appears to be a Rubyism) with
"little language": http://wiki.c2.com/?LittleLanguage

-- 
--Guido van Rossum (python.org/~guido)
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[David Mertz]

On Thu, Aug 30, 2018 at 9:41 PM Guido van Rossum  wrote:

> On Fri, Aug 31, 2018 at 3:19 AM, Michael Selik  wrote:
>
>> On Thu, Aug 30, 2018 at 5:31 PM James Lu  wrote:
>>
>>> It would be nice if there was a DSL for describing neural networks
>>> (Keras).
>>>
>>> model.add(Dense(units=64, activation='relu', input_dim=100))
>>> model.add(Dense(units=10, activation='softmax'))
>>>
>>>
>> Why not JSON or XML for cross-language compatibility?
>>
>
> Presumably because those are even harder to read and write for humans.
>

Guido is absolutely right (as usual) that JSON or XML would be *vastly*
harder to read than that very clean Python code.

That said, if you wanted a "DSL", the perfect choice would be YAML.  The
description above could look like this:

>>> model = '''
... model:
...   - layer: Dense
... units: 64
... activation: relu
... input_dim: 100
...   - layer: Dense
... units: 10
... activation: softmax
... '''
>>> yaml.load(model)
{'model': [{'layer': 'Dense', 'units': 64, 'activation': 'relu',
'input_dim': 100}, {'layer': 'Dense', 'units': 10, 'activation':
'softmax'}]}


This format could easily be either a string within a Python program or an
external file with the definition.  YAML is already well supported in
Python, all you'd need to do is write a little wrapper to translate the
description above into the actual Keras API calls, which would be pretty
easy.


-- 
Keeping medicines from the bloodstreams of the sick; food
from the bellies of the hungry; books from the hands of the
uneducated; technology from the underdeveloped; and putting
advocates of freedom in prisons.  Intellectual property is
to the 21st century what the slave trade was to the 16th.
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Guido van Rossum]

On Fri, Aug 31, 2018 at 3:19 AM, Michael Selik  wrote:

> On Thu, Aug 30, 2018 at 5:31 PM James Lu  wrote:
>
>> It would be nice if there was a DSL for describing neural networks
>> (Keras).
>>
>> model.add(Dense(units=64, activation='relu', input_dim=100))
>> model.add(Dense(units=10, activation='softmax'))
>>
>>
> Why not JSON or XML for cross-language compatibility?
>

Presumably because those are even harder to read and write for humans.

I believe that the key issue with using Python as a DSL has to do with its
insistence on punctuation -- the above example uses nested parentheses,
commas, equal signs, and quotation marks. Those are in general needed to
avoid ambiguities, but DSLs are often highly stylized, and a language that
doesn't need them has a certain advantage. For example if a shell-like
language was adopted, the above could probably be written with spaces
instead of commas, parentheses and equal signs, and dropping the quotes
(though perhaps it would be more readable if the equal signs were kept).

I'm not sure how we would go about this though. IIRC there was a proposal
once to allow top-level function calls to be written without parentheses,
but it was too hard to make it unambiguous (e.g. would "foo +1" mean
"foo(+1)" or "foo + 1"?)

-- 
--Guido van Rossum (python.org/~guido)
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Why shouldn't Python be better at implementing Domain Specific Languages?

[Michael Selik]

On Thu, Aug 30, 2018 at 5:31 PM James Lu  wrote:

> It would be nice if there was a DSL for describing neural networks (Keras).
>
> model.add(Dense(units=64, activation='relu', input_dim=100))
> model.add(Dense(units=10, activation='softmax'))
>
>
Why not JSON or XML for cross-language compatibility?
___
Python-ideas mailing list
Python-ideas@python.org
https://mail.python.org/mailman/listinfo/python-ideas
Code of Conduct: http://python.org/psf/codeofconduct/