Racket 7.3

https://download.racket-lang.org/v7.3.html

by jessealama • 7 years ago

287 53 7 years ago

nerdponx2• 7 years ago

And yet I'm still too stupid to understand the macro system. Oh well.

I also didn't know there was a Chez version. Racket already has a native AOT compiler, right? What would the advantage be to run on Chez, faster or smaller compiled code?

swdunlop• 7 years ago

See http://blog.racket-lang.org/2019/01/racket-on-chez-status.ht... and scroll down to “Performance of Compiled Code.” That was back in January, so things may be even better now.

jim-jim-jim• 7 years ago

Is it the general Scheme syntax-rules macros that you're struggling with? Or something unique to Racket? (which I haven't used)

If it's the former, I found this little article helpful when I was new to Scheme:

http://www.willdonnelly.net/blog/scheme-syntax-rules/

tgbugs• 7 years ago

For Racket specific macro tooling syntax-parse [0] in combination with syntax classes is usually the suggested starting point. Hygenic with pattern matching and a bunch of other features for parsing s-expression grammars. As mentioned down-thread Greg Hendershott's Fear of Macros [1] is a good starting point for a number of folks. The curriculum for Racket School 2018 [2] also has exercises that help introduce the syntax-parse tooling.

0. https://docs.racket-lang.org/syntax/Parsing_Syntax.html 1. https://www.greghendershott.com/fear-of-macros/ 2. https://summer-school.racket-lang.org/2018/plan/

xabush• 7 years ago

This is great tutorial. I used to be confused by the macros in scheme

pjmlp• 7 years ago

Getting rid of C dependency and bootstrap Racket in Scheme.

darkpuma• 7 years ago

Try out this guide perhaps: http://www.greghendershott.com/fear-of-macros/

pyb• 7 years ago

A few people exist who are genuinely able to use Racket macros, but they all have a PhD in CS.

As opposed to the larger group who think they understand them. I was once in that group, but now I've just given up.

NikkiA2• 7 years ago

Racket's macro transformers are about as easy as hygenic macros[0] get unfortunately, I can occasionally manage to make a er-macro-transformer based macro in chicken work how I want.

defmacro was a lot easier, but I understand the aversion to it, even if it was rare that it was/is a problem.

[0] syntax-rules based macros are cake, naturally, but they're also incredibly limited, although I have seen people implement massive complex OO systems using a sort of ad-hoc state machine built in pages upon pages of syntax-rules rules.

Bogdanp3• 7 years ago

And yet I'm still too stupid to understand the macro system. Oh well.

This talk[0] by Robby Findler helped me a ton when I was first learning about macros in Racket. I've found that the best way to learn, though, is by doing: when you find a use case for a macro, figure out how to do that particular thing and, slowly but surely, things will start to click.

[0] https://www.youtube.com/watch?v=hFlIl0Zo234

gus_massa• 7 years ago

For the macros, I prefer to recommend to start with very straightforward macros that use `define-syntax-rule`. For example

  #lang racket
  
  (define-syntax-rule (run3times code ...)
    (begin
      (begin code ...)
      (begin code ...)
      (begin code ...)))
  
  (define x 0)
  
  (run3times
    (set! x (add1 x))
    (display x))      ; shows ==> 123

As other comment said, you have to find some good opportunity to use a simple macro.

(In this case, it is better to use the build-in `for`. Actually, `for` is defined in a macro, it is not part of the internal "secret" low level language.)

Once you are confident and you grok the difference between a macro and a function, you can try the other ways to define macros. These other ways are more flexible and can make weirder macros, and have better support when the macro is used wrongly. There are good links in the sibling comments.

GeoffKnauth• 7 years ago

Another way to learn about all this stuff from the experts themselves is Racket School: https://school.racket-lang.org/

Labo3332• 7 years ago

I am really excited by Racket.

Unlike most minimalist LISP languages with a community of individual hackers who each have their own macros and packages, this one is battery included while still being the most flexible with the #lang header. Seriously, it comes with awesome data structures (actuelly more than Python).

The only thing that prevents me from using it as much as Python or C++ is the lack of tools for major editors. DrRacket is NOT ok, I would like a langserver and vscode extension so badly! When I have a bit of free time and have finished other projects with a higher priority, I'll definitely give it a try. (yes I'm aware there are some langservers but none of them is really production ready)

Veen3• 7 years ago

Emacs has a decent Racket mode with most of the functionality of DrRacket.

soegaard• 7 years ago

These days racket-mode for Emacs is more than decent!

Could wish for similar modes for SublimeText and VisualCode though.

Labo3332• 7 years ago

Thanks for the pointer, I'll try and see whether I can port racket-mode as a vscode extension.

yomly• 7 years ago

Do Naughty Dog still use Racket? Anyone from there able to give some insight into what tools/dev environment they use there?

ctas2• 7 years ago

No they don't. AFAIK they moved away from Racket. I once contacted them for potential open positions I could list on racketjobs.com (I'm the creator).

nerdponx2• 7 years ago

A Racket language server would be great. I wonder if some DrRacket internals could be spun off.

cabernal• 7 years ago

Here you go: https://docs.racket-lang.org/racket-language-server/index.ht...

cercatrova2• 7 years ago

VS Code has a pretty good one

https://marketplace.visualstudio.com/items?itemName=evzen-wy...

Eugeleo• 7 years ago

Hey, author here! The extension is only a syntax highlighting one atm (albeit a pretty good one, I hope), but I have bigger plans for it. The problem is, the development of Racket LSP has slowed a lot as of late, and I'm not skilled enough to make one myself.

stesch2• 7 years ago

Font looks like shit in Firefox on macOS X.

laszlokorte• 7 years ago

Maybe link to the blog post [1] instead.

[1] https://blog.racket-lang.org/2019/05/racket-v7-3.html

Veen3• 7 years ago

For reasons I find difficult to understand, the text is between <pre> tags and uses a monospace font (Inconsolata). It is curious that a project that cites Matthew Butterick as a contributor should make such poor decisions about typography, especially when the rest of the documentation is above average in that area.

velcrovan• 7 years ago

Matthew is a contributor, doesn't mean he is the Jony Ive of every single web page they publish.

dragonwriter• 7 years ago

It's wrapped in <pre> tags because it is preformatted text of the type that would be used in email, etc., announcements (probably becauae it's the exact text from those media, without transformation), so not using <pre> would lose significant formatting.

Of course, the formatting is broken anyway, because two of the continuation lines of bullet-pointed lines are underindented by one space.

lenkite3• 7 years ago

I really wish there was a standard Scheme that compiled to native for all desktop and mobile OS'es and also supported multi-threading. Does anyone know about one ?

rgrau3• 7 years ago

LambdaNative is a cross-platform development environment written in Scheme, supporting Android, iOS, BlackBerry 10, OS X, Linux, Windows, OpenBSD, NetBSD, FreeBSD and OpenWrt.

http://www.lambdanative.org/

lenkite3• 7 years ago

LambdaNative is a wrapper and abstraction over Gambit Scheme. It does not support multi-core threading.

Bogdanp3• 7 years ago

Racket does tick some of those boxes:

* it has support for OS-level threads via places[0]

* it can produce binary distributions via `raco distribute`[1] by packing together the interpreter and your compiled code into a single executable

* while the current implementation is based on a bytecode-compiler and VM, I believe the Chez implementation actually compiles to native code (although the whole process is transparent to the user)

* it is possible to run Racket on ARM devices, in fact there was a recent thread[2] about that on the mailing list

I realize this isn't 100% what you're looking for, but Racket does come with many nice features. Alternatively, you might also want to take a look at CHICKEN Scheme[3].

[0] https://docs.racket-lang.org/guide/parallelism.html#%28part....

[1] https://docs.racket-lang.org/raco/exe-dist.html

[2] https://groups.google.com/forum/#!topic/racket-users/YEajWJe...

[3] https://call-cc.org/

bjourne2• 7 years ago

Is typed racket still very slow? I'm interested in hearing how Racket's gradual typing works.

Bogdanp3• 7 years ago

It depends upon what you mean by slow. Typed Racket code compiles more slowly than normal Racket code, but should run about as fast or faster (for a small set of specifically-typed code[0]).

[0] https://docs.racket-lang.org/ts-guide/optimization.html

chriswarbo2• 7 years ago

Typed racket isn't slow (as far as scripting languages go). Maybe you're thinking of Racket's "contract" system?

AFAIK typed racket does type-checking during compilation (via raco); the resulting code is no slower than normal Racket, although I'm not sure if it's faster either.

The contract system is different; it works on normal, untyped Racket code and performs checks at runtime; similar to using Python decorators to check the input and output of a function. This slows things down, so it's recommended to only check things at module boundaries. For example:

    #lang racket
    (require racket/contract)
    (require racket/match)
    (provide factorial)

    (define/contract (factorial n)
      (-> exact-nonnegative-integer?
          exact-nonnegative-integer?)
      (fact n))

    (define (fact n)
      (match n
        [0 1]
        [_ (* n (fact (- n 1)))]))

This module exposes the `factorial` function, which checks (at runtime) whether its argument and return value are non-negative integers (i.e. 0, 1, 2, ...). The actual calculation is done by the `fact` function, which is private and doesn't do any checks. If we don't separate the checks from the calculation, we would end up running the checks on every recursive call, which would slow things down a lot.

As far as I'm aware, Racket's gradual typing is done by contracts at the interface between typed and untyped code. Hence it's not that typed racket is slow, it's that passing untyped values into typed functions can be slow, if we want accurate blame information for errors.

bjourne2• 7 years ago

I'm referring to Takikawa et al (2016), who reported performance 50-100 times worse performance numbers by mixing typed and untyped Racket code together. Actually 100 times slower execution. They used type annotations on the module level. Would be interesting to know if Racket developers have proven them wrong and if so, how.

http://www.ccis.northeastern.edu/home/types/publications/gra...

Racket 7.3

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