6 ms·

Rosencrantz – A Web DSL for Nim

69 points by Varriount 10y ago

PostThisTooFast 10y ago
People still use DSL?
keyle 10y ago
Nim is one of those underpublicized language. It's really good, I will leave it at that. I've used it a few times and it takes maybe 10 minutes to get back into it. It's perfect for making tools.
- styluss 10y ago
  What did you use it for?
- Gonzih 10y ago
  Yeah, I also had positive experience with nim. I'm not sure why it's so unknown, maybe because it fits in the same niche between rust and go and not backed up by any major company in industry. But I highly recommend trying Nim out!
  - biokoda 10y ago
    > not backed up by any major company That is pretty much the entire reason. Any technology not being backed by a large player in the industry has a much tougher time getting traction.
  - deleted 10y ago
    [deleted]
  - Bromskloss 10y ago
    Are Rust and Go in the same niche?
    - Gonzih 10y ago
      No, not really. But nim in my opinion is something in between.
  - 3pt14159 10y ago
    Nim is great, and I use it (in production), but I know exactly why it isn't as popular: Nim is fucking huge. Most programmers I know don't even know what a pragma is; Nim uses them extensively. Nim has types, objects, is low level, can be compiled to shared objects (something that didn't come out to Go until 1.5), macros, generics, templates, oh and it compiles to both C and JavaScript (and C++, and Objective C in case you need easy bindings for those), dynamic dispatch, mutually recursive types, pointers, named arguments, tricky hash tables, procedures that look like functions or methods (whichever suits you), and an irrelevant casing (spellLikeThis is the same is spell_like_this - case only matters for the first letter and underscores don't matter), and many more. All of this on top of a hyper fast (~2x the speed of Go) compiled language. Most other very complete languages are not compiled so you can kinda muck around in a repl and use introspection to figure out whats going on. Nim isn't like that. You need to think and figure things out when you're first learning it. Furthermore Nim isn't yet at 1.0 and lacks its killer library. Go and Rust are easier to get started with because they are simpler languages. They are easier to teach and easier to write documentation for. Nim kinda reminds me of Ember or Rails or C++(see note): Huge, but worthwhile to learn because you'll never feel constrained by it. I highly doubt it will ever be as mainstream as Go though. I've generally found that most people are too lazy to learn harder languages / libraries. Note: I do not like C++ for many reasons. The tooling is crufty, syntax is awful, impossible to reason about a codebase unless its picked a subset of C++; but the one thing I'll grant C++ is that you can always eventually get what you want done.
    - nickpsecurity 10y ago
      What you've just described is a hodgepodge of stuff thrown together. That's a lack of language design with a surplus of features. My readings on older reports for language designs showed the art was figuring out just how much power to include in the language & keeping it all consistent/sensible. One can overdo it. An example of a clean, carefully-thought language that's low-level, consistent, and very powerful is PreScheme: https://en.wikipedia.org/wiki/PreScheme https://en.wikipedia.org/wiki/PreScheme Modula-3, a C++ and Java competitor, was another where they made careful tradeoffs of features, safety, compile speed, run speed, and ease of learning/reading. https://en.wikipedia.org/wiki/Modula-3 https://en.wikipedia.org/wiki/Modula-3 There's also some dialects of Haskell and ML focusing on system level. Didn't hit those levels of maturity though. What I'd like to see is someone take the Nim tech, subset it, change inconsistent stuff to be consistent... basically clean it up into a coherent picture... then deploy that as a new language. It could be pretty awesome if it happens. Right now, it's too complex and incoherent except for people, as you said, willing to do a huge learning curve. Note: Nim is so huge now that it might be easier to add Ada static checks and Rust dynamic/concurrency checks to PreScheme instead of fixing Nim. You'd have a low-level, safe LISP. Put a 3GL front end on top of it for more adoption. That's what Julia people did.
- Bromskloss 10y ago
  > It's perfect for making tools. What does "tools" mean here and what is it about the language that makes it suitable for writing such things? Edit: I fear I might have sounded snarky here, but it's just my "I want to learn" voice.
Cyph0n 10y ago
This is inspired by Spray, which I just learned about recently. The project is being migrated to Akka, so it's going to have support for the foreseeable future. It looks like a great fit for Nim though.
k__ 10y ago
Sad to see all these [] and () in Nim, which has such a beautiful syntax to start with.
- pathsjs 10y ago
  What would you suggest instead? Routes are naturally nested, and overloading [] seemed the best choice
  - Nycto 10y ago
    I came here to say the same thing as the GP. So while I am not the poster you responded to, I'll pitch in my opinion. I've written a number of Nim libs at this point. Rosencrantz is missing the idiomatic 'feel' of Nim -- blocks and trees. I would rather see a syntax like this: let handler = firstOf: get: firstOf: path("/api/status"): ok(getStatus()) pathChunk("/api/message"): accept("application/json"): intSegment(id): let message = getMessageById(id) ok(message) post: path("/api/new-message"): jsonBody(msg): let id = generateId() saved = saveMessage(id, msg) if saved: ok(id) else: complete(Http500, "save failed") I believe all of that should be possible using templates; grab the AST for the `stmt` passed to each function, then iterate over each node.
    - pathsjs 10y ago
      The problem with this approach is that it would be difficult to make handlers first-class. What if your post routes are a handler imported from another module? Templates would allow for the syntax you present, but do not combine.
      - Nycto 10y ago
        That's not at all the case. Templates can return values. So really, you could think of the templates as syntactic sugar around the existing functions you've got right now. For example, the 'firstOf' template above would be responsible for scanning the AST it's given, taking each node and putting it in to a sequence. Then it instantiates a Handler with that sequence and returns it.
egeozcan 10y ago
Why not Jester[1]? Jester has a better API, IMO. [1]: https://github.com/dom96/jester https://github.com/dom96/jester
- pathsjs 10y ago
  I wrote Rosencrantz because I do not like the Jester API very much. Jester, like many other frameworks, hardcodes exactly what to do with a Request - say parsing the headers, parsing the form if the content type suggests so, always return a date, and so on. This is not bad per se, but I prefer to have something I can compose. Say, I have a working route `r`. If I want to add CORS support, for instance, I can just make a handler `h` that adds CORS headers and then use the route `h -> r`. This is more flexible and leaves fine grained control over which headers to require, or return, how to do content negotiation, and so on. You can separate your routes for `POST` from those for `GET` in different modules and then combine them, or maybe separate your authentication routes from the business logic ones. You can easily create handlers that work as middleware, and so on. In short, the thing I like about this approach is that handlers become first class objects that you can manipulate and create freely
  - egeozcan 10y ago
    I see. So, hopefully not being too shallow, this is like Jester with middleware support. I'll give it a try.
dom96 10y ago
Slightly off-topic but related to Nim. Having been inspired by the Rust community survey we have just created a similar one for Nim. I would appreciate any and all answers, especially if you've never used Nim before! http://goo.gl/forms/XJ3TPsaiIQe5HlTB2 http://goo.gl/forms/XJ3TPsaiIQe5HlTB2
vittore 10y ago
Now I am waiting for a web server Guildenstern in Nim.

69 points by Varriount 10y ago

People still use DSL?

keyle 10y ago

Nim is one of those underpublicized language. It's really good, I will leave it at that. I've used it a few times and it takes maybe 10 minutes to get back into it. It's perfect for making tools.

styluss 10y ago
What did you use it for?
Gonzih 10y ago
Yeah, I also had positive experience with nim. I'm not sure why it's so unknown, maybe because it fits in the same niche between rust and go and not backed up by any major company in industry. But I highly recommend trying Nim out!
- biokoda 10y ago
  > not backed up by any major company That is pretty much the entire reason. Any technology not being backed by a large player in the industry has a much tougher time getting traction.
- deleted 10y ago
  [deleted]
- Bromskloss 10y ago
  Are Rust and Go in the same niche?
  - Gonzih 10y ago
    No, not really. But nim in my opinion is something in between.
- 3pt14159 10y ago
  Nim is great, and I use it (in production), but I know exactly why it isn't as popular: Nim is fucking huge. Most programmers I know don't even know what a pragma is; Nim uses them extensively. Nim has types, objects, is low level, can be compiled to shared objects (something that didn't come out to Go until 1.5), macros, generics, templates, oh and it compiles to both C and JavaScript (and C++, and Objective C in case you need easy bindings for those), dynamic dispatch, mutually recursive types, pointers, named arguments, tricky hash tables, procedures that look like functions or methods (whichever suits you), and an irrelevant casing (spellLikeThis is the same is spell_like_this - case only matters for the first letter and underscores don't matter), and many more. All of this on top of a hyper fast (~2x the speed of Go) compiled language. Most other very complete languages are not compiled so you can kinda muck around in a repl and use introspection to figure out whats going on. Nim isn't like that. You need to think and figure things out when you're first learning it. Furthermore Nim isn't yet at 1.0 and lacks its killer library. Go and Rust are easier to get started with because they are simpler languages. They are easier to teach and easier to write documentation for. Nim kinda reminds me of Ember or Rails or C++(see note): Huge, but worthwhile to learn because you'll never feel constrained by it. I highly doubt it will ever be as mainstream as Go though. I've generally found that most people are too lazy to learn harder languages / libraries. Note: I do not like C++ for many reasons. The tooling is crufty, syntax is awful, impossible to reason about a codebase unless its picked a subset of C++; but the one thing I'll grant C++ is that you can always eventually get what you want done.
  - nickpsecurity 10y ago
    What you've just described is a hodgepodge of stuff thrown together. That's a lack of language design with a surplus of features. My readings on older reports for language designs showed the art was figuring out just how much power to include in the language & keeping it all consistent/sensible. One can overdo it. An example of a clean, carefully-thought language that's low-level, consistent, and very powerful is PreScheme: https://en.wikipedia.org/wiki/PreScheme https://en.wikipedia.org/wiki/PreScheme Modula-3, a C++ and Java competitor, was another where they made careful tradeoffs of features, safety, compile speed, run speed, and ease of learning/reading. https://en.wikipedia.org/wiki/Modula-3 https://en.wikipedia.org/wiki/Modula-3 There's also some dialects of Haskell and ML focusing on system level. Didn't hit those levels of maturity though. What I'd like to see is someone take the Nim tech, subset it, change inconsistent stuff to be consistent... basically clean it up into a coherent picture... then deploy that as a new language. It could be pretty awesome if it happens. Right now, it's too complex and incoherent except for people, as you said, willing to do a huge learning curve. Note: Nim is so huge now that it might be easier to add Ada static checks and Rust dynamic/concurrency checks to PreScheme instead of fixing Nim. You'd have a low-level, safe LISP. Put a 3GL front end on top of it for more adoption. That's what Julia people did.
Bromskloss 10y ago
> It's perfect for making tools. What does "tools" mean here and what is it about the language that makes it suitable for writing such things? Edit: I fear I might have sounded snarky here, but it's just my "I want to learn" voice.

Cyph0n 10y ago

This is inspired by Spray, which I just learned about recently. The project is being migrated to Akka, so it's going to have support for the foreseeable future. It looks like a great fit for Nim though.

k__ 10y ago

Sad to see all these [] and () in Nim, which has such a beautiful syntax to start with.

pathsjs 10y ago
What would you suggest instead? Routes are naturally nested, and overloading [] seemed the best choice
- Nycto 10y ago
  I came here to say the same thing as the GP. So while I am not the poster you responded to, I'll pitch in my opinion. I've written a number of Nim libs at this point. Rosencrantz is missing the idiomatic 'feel' of Nim -- blocks and trees. I would rather see a syntax like this: let handler = firstOf: get: firstOf: path("/api/status"): ok(getStatus()) pathChunk("/api/message"): accept("application/json"): intSegment(id): let message = getMessageById(id) ok(message) post: path("/api/new-message"): jsonBody(msg): let id = generateId() saved = saveMessage(id, msg) if saved: ok(id) else: complete(Http500, "save failed") I believe all of that should be possible using templates; grab the AST for the `stmt` passed to each function, then iterate over each node.
  - pathsjs 10y ago
    The problem with this approach is that it would be difficult to make handlers first-class. What if your post routes are a handler imported from another module? Templates would allow for the syntax you present, but do not combine.
    - Nycto 10y ago
      That's not at all the case. Templates can return values. So really, you could think of the templates as syntactic sugar around the existing functions you've got right now. For example, the 'firstOf' template above would be responsible for scanning the AST it's given, taking each node and putting it in to a sequence. Then it instantiates a Handler with that sequence and returns it.

egeozcan 10y ago

Why not Jester[1]? Jester has a better API, IMO. [1]: https://github.com/dom96/jester https://github.com/dom96/jester

pathsjs 10y ago
I wrote Rosencrantz because I do not like the Jester API very much. Jester, like many other frameworks, hardcodes exactly what to do with a Request - say parsing the headers, parsing the form if the content type suggests so, always return a date, and so on. This is not bad per se, but I prefer to have something I can compose. Say, I have a working route `r`. If I want to add CORS support, for instance, I can just make a handler `h` that adds CORS headers and then use the route `h -> r`. This is more flexible and leaves fine grained control over which headers to require, or return, how to do content negotiation, and so on. You can separate your routes for `POST` from those for `GET` in different modules and then combine them, or maybe separate your authentication routes from the business logic ones. You can easily create handlers that work as middleware, and so on. In short, the thing I like about this approach is that handlers become first class objects that you can manipulate and create freely
- egeozcan 10y ago
  I see. So, hopefully not being too shallow, this is like Jester with middleware support. I'll give it a try.

dom96 10y ago

Slightly off-topic but related to Nim. Having been inspired by the Rust community survey we have just created a similar one for Nim. I would appreciate any and all answers, especially if you've never used Nim before! http://goo.gl/forms/XJ3TPsaiIQe5HlTB2 http://goo.gl/forms/XJ3TPsaiIQe5HlTB2

vittore 10y ago

Now I am waiting for a web server Guildenstern in Nim.