Pyret: A new programming language from the creators of Racket • Hacker News Board

Re: Pyret: A new programming language from the creators of Racket

#41

Post by driax » Sat, Nov 09, 2013, 4:23 PM UTC

6ren wrote: post #16

terhechte wrote: post #3

"""Pyret makes testing a natural part of the programming process. Functions can end in a where: clause that holds unit tests for the function. These assertions are checked dynamically.""" Fantastic idea! I'll keep that in mind, should be fairly easy to extend Lisps or other AST-Macro enabled languages (Elixir, Julia, Python) with such a functionality. I really like that. It makes it easy to work on a function and cod…

It clutters the code. Tests are a form of documentation, but too much in the code, like too many comments, obscures. Higher level unit tests (acceptance tests) can be quite long, especially if there's a lot of setup - unlike their example code. Literate programming tried embedded documentation, but didn't catch on (even with Knuth's backing). Embedding tests makes them easier to keep in sync, but tests are already ke…

On the other hand, inline test does make it easier to write tests while writing the function. Besides many well-written programs already contains inline documentation (not comments) that can be a lot longer than the function they describes.

Code folding in a IDE goes a long way to make this bearable.

Re: Pyret: A new programming language from the creators of Racket

#42

Post by gizmo » Sat, Nov 09, 2013, 4:24 PM UTC

PhineasRex wrote: post #20

gizmo wrote: post #7

Pyret looks like a there's a lot going on, based on the examples. It has implicit returns, special purpose syntax for data structures, iterators, assertions, refinements, etc. Having support for more stuff makes it less suitable as a teaching language, not more. Pyret looks like a has the good bits of Python plus a whole bunch of other cool stuff. But the language is pretty complex as a result. Cool? Yup! Good for te…

By that logic, assembly is the best language to learn programming. Presumably it is easier to learn about concepts with a language that has them.

Obviously I'm not suggesting that assembler is the best teaching language. I could also take your logic and use it to conclude that C++ is the best programming language to learn first because with C++ you can learn about the implications of heap corruption when improperly handling exceptions in constructors. C++ allows functional, procedural and OO and many more programming styles. It supports manual and automatic memory management. It can be used to teach high level and low level programming constructs. But I think we're all in agreement that C++ is not a good first language to learn despite (or because of) its versatility.

I think Python is a very accessible programming language that still has enough depth to go into a lot of interesting CS subjects. That Python doesn't have manual memory management or support for true multiple inheritance means that you can't teach those things effectively with Python, and I'm completely OK with that trade-off.

Re: Pyret: A new programming language from the creators of Racket

#43

Post by laureny » Sat, Nov 09, 2013, 4:24 PM UTC

ash wrote: post #9

terhechte wrote: post #3

"""Pyret makes testing a natural part of the programming process. Functions can end in a where: clause that holds unit tests for the function. These assertions are checked dynamically.""" Fantastic idea! I'll keep that in mind, should be fairly easy to extend Lisps or other AST-Macro enabled languages (Elixir, Julia, Python) with such a functionality. I really like that. It makes it easy to work on a function and cod…

Making tests part of language syntax is an interesting idea. Of course it's not equivalent, but Python doctest module at least allows you to keep tests close to the code. Here's Pyret example, ported to doctest: def sum(l): """ >>> sum([]) 0 >>> sum([1, 2, 3]) 6 """ return reduce(lambda x, y: x+y, l, 0) if __name__ == "__main__": import doctest; doctest.testmod()

> Making tests part of language syntax is an interesting idea.

It's been tried many times before and it has always failed. A few reasons:

- It clutters the code

- If you need simple tests, asserts suffice

- If you need more sophisticated tests, write functional tests, separately

The approach offered by Pyret (along with similar ones, such as design by contract) are compromises that are the worst of both worlds.

Re: Pyret: A new programming language from the creators of Racket

#44

Post by L8D » Sat, Nov 09, 2013, 4:28 PM UTC

pekk wrote: post #31

Looks more like Ruby than Python, why the comparison to Python?

Where Ruby usually denotes code blocks with a `do` and an `end`, Python denotes code blocks with a `:` and an outdent. But also, Ruby has a lot more implicit syntax and uses methods as operators(`1 + 1 == 1.+(1)`). There are a few more things that wouldn’t be obvious, like how it is still indentation sensitive yet you still need to use an `end`. Also, you can avoid the `end` keyword is you include it on the same line, like so:

    fun square(n): n * n

Re: Pyret: A new programming language from the creators of Racket

#45

Post by jkscm » Sat, Nov 09, 2013, 4:28 PM UTC

gizmo wrote: post #7

Pyret looks like a there's a lot going on, based on the examples. It has implicit returns, special purpose syntax for data structures, iterators, assertions, refinements, etc. Having support for more stuff makes it less suitable as a teaching language, not more. Pyret looks like a has the good bits of Python plus a whole bunch of other cool stuff. But the language is pretty complex as a result. Cool? Yup! Good for te…

Language complexity may not matter much.

"He speculated that the size of programming languages might confuse many students trying to learn to program. Java, the teacher’s programming language of choice at the end of the 20th century and at the beginning of the 21st, is defined loosely but at great length in several hundred pages.4 Natural Deduction, on the other hand, can be defined precisely on a single side of a single A4 sheet, in a normal font size. It is small and conceptually simple: surely it can be taught! Well, up to a point it can, but the results were depressingly familiar. Figure 14 shows the results from an in-course exam on formal logical proof. Unlike the examinations of section 3, students were strongly discouraged from guessing, with negative marks for wrong answers in multiple-choice questions and extensive unseen proof problems. As a consequence, two humps are clearly visible, with one at 33-40 (about 50%) and another at 65-72 (about 85%). (This data was collected long before Dehnadi’s test was developed, so we can’t analyse it further)."

Saeed Dehnadi - The camel has two humps (working title): http://mrss.dokoda.jp/r/http://www.eis.mdx.ac.uk/research/Ph...

Re: Pyret: A new programming language from the creators of Racket

#46

Post by chongli » Sat, Nov 09, 2013, 4:29 PM UTC

andybak wrote: post #12

klrr wrote: post #10

This project seems really promising, but I got one concern. Lisp's syntax have been one of its strength for beginners. Easy to learn, easy to solve common errors. I don't see the point of having Python-like syntax really, the user could learn other syntax after they've understood programming .

My jaw dropped slightly to see someone suggest Lisp syntax would be a better starting place for beginners than Python's syntax. Is it just me or is that a fairly unorthodox point of view?

The key word is beginners. The people who have the most trouble with Lisp syntax are those already accustomed to other languages. Beginners pick it up with no trouble at all.

Re: Pyret: A new programming language from the creators of Racket

#47

Post by rmc » Sat, Nov 09, 2013, 4:37 PM UTC

terhechte wrote: post #3

"""Pyret makes testing a natural part of the programming process. Functions can end in a where: clause that holds unit tests for the function. These assertions are checked dynamically.""" Fantastic idea! I'll keep that in mind, should be fairly easy to extend Lisps or other AST-Macro enabled languages (Elixir, Julia, Python) with such a functionality. I really like that. It makes it easy to work on a function and cod…

AST-Macro enabled languages (... Python)

What?! You can't write macros in Python? (right? have I missed something?)

Re: Pyret: A new programming language from the creators of Racket

#48

Post by clhodapp » Sat, Nov 09, 2013, 4:39 PM UTC

ek wrote: post #32

clhodapp wrote: post #19

Earlier quoted context omitted.

I think you mean that it's in opposition to their goal of being easy to learn, not that it's orthogonal, as that would mean "it doesn't interfere". Anyway, it seems to me that the only real difference between your code examples is that the second one lacks an ending designator and uses an equals-sign instead of a colon. However, in order to make the lack of an ending designator work, you need a more complex parser (i…

Newlines are not a fine separator; what if you have a definition that you intend to span multiple lines? In any case, the pipes go all the way back to EBNF, since what you are really doing when you specify an ADT is specifying a grammar of types. I admit to also being a brace weenie; I would very much prefer if all the languages I had to use had them. However, Pyret exists in a tradition of many successful, braceless…

I feel that the argument for the need for multiline definitions here is a bit weak. You are already putting each definition on its own line, so the definitions are actually fairly close to how their actual usage will look. I feel that if you really need them to be all that long, you are already in weird-style territory, so it isn't such a bad idea to just say "deal with wide files". Overall, it improves ergonomics for the vast majority of use cases, with the only cost being a possible aesthetic annoyance for users who are already writing aesthetically-annoying code.

Re: Pyret: A new programming language from the creators of Racket

#49

Post by sparkie » Sat, Nov 09, 2013, 4:41 PM UTC

andybak wrote: post #12

klrr wrote: post #10

This project seems really promising, but I got one concern. Lisp's syntax have been one of its strength for beginners. Easy to learn, easy to solve common errors. I don't see the point of having Python-like syntax really, the user could learn other syntax after they've understood programming .

My jaw dropped slightly to see someone suggest Lisp syntax would be a better starting place for beginners than Python's syntax. Is it just me or is that a fairly unorthodox point of view?

I'd say the real trouble is teaching any syntax at all to beginners, because their first language really taints them for life. Most people will think of successive languages in terms of their first, until they learn many and are able to think more generally.

Lisp has the advantage that it really teaches the general semantics of programming languages, because it's syntax is just the syntax tree, and it basically only has one form, which is function application. There's some "special forms" built into the implementation of a lisp to make it useful, but those shouldn't be confused with syntax. In fact, the parenthesis and space between function and arguments shouldn't be considered the lisp syntax either - it's just one way to represent a tree structure in linear text.

I think the real issue is the confusion in teaching is between Computer Science and Computing as a vocation. Nobody teaches the former any more, because it's less useful in the real world. As a result, we have languages which try to make a distinction between "programmer" and "programming language implementer", where the programmer generally knows less about what he is doing because someone has imposed a specific, narrow set of ideas on him.

Re: Pyret: A new programming language from the creators of Racket

#50

Post by rhizome31 » Sat, Nov 09, 2013, 4:47 PM UTC

tel wrote: post #2

Python-like syntax with pattern matching and recursive ADTs!? What a great idea!

+1

This looks a lot like the language I've been dreaming about. I actually like the explicit `end` keyword to materialize the end of blocks. The lambda expression syntax, as illustrated by the filter/map/fold example, looks like Ruby blocks with a much simpler syntax. A couple of questions to the crew:

Why advertise it as a teaching language ? As a working programmer this looks very appealing to me. Are there limitations that don't make it a good language for practical programming (other than the fact that it's not ready yet, of course)?

Are you planning to provide a tutorial more approachable than the language reference?