2) Dialyzer works fine on Elixir beam files. You can specify type & spec attributes just like in Erlang.
If macros worry you unduly, then Elixir is not for you. I personally prefer to use macros than type lots of boilerplate code, but yes there are some downsides.
edit: Actually I should have said reading and typing - reading boilerplate is much worse than writing it. Judicious use of macros can clarify intent for someone reading the code.
1) A language introduction is not documentation, and is certainly not specification. It's difficult to discuss a new language when you have to guess how it works based on a handful of examples.
2) Dialyzer is a complete, not sound program analyzer. i.e. it will never produce a false positive, but it may allow incorrect programs through. By making definitions first-class, Elixir's module language becomes Turing-complete, moving a whole new class of bugs into Dialyzer's "false negative" category.
This problem doesn't exist with second-class definition systems such as OCaml's, because the definition language is not Turing-complete: all definitions and modules may be checked at compile time.
3) I'm not sure where macros come into play? Are you using "macros" to mean "higher-order programming tools"? If so, you're misunderstanding me -- I use metaprogramming tools all the time; I simply prefer ones which aren't Turing-complete and are therefore amenable to analysis.
> It's difficult to discuss a new language when you have to guess how it works based on a handful of examples.
It sounds like you are more interested in "CS friendly" languages, rather than "get stuff done" languages. Erlang and Elixir tend toward the latter category.
I'm generalizing a lot, and that's not to say a language can't be both, but Erlang was born of a practical need, and I think that Elixir is similar: it's not meant to be the most beautiful language out there, it's meant to be a bit more user-friendly way of utilizing the power of Erlang and OTP.
In terms of a specification, have a look at Elixir's test suite. Given that it's still being hacked on, it's probably not set in stone.
It sounds like you are more interested in "CS friendly" languages, rather than "get stuff done" languages.
It sounds like you think there's no overlap (despite your next paragraph).
Additionally: "CS friendliness" is more pragmatic than you think. Automatic refactoring and automatic code analysis are two huge pragmatic wins (think: saving developer time) that are made possible only by paying heed to analyzability of code.
Erlang and Elixir tend toward the latter category.
Erlang is my current favorite language. You may not realize it, but it is one of the most "CS friendly" mainstream languages that exist. The fact that it is almost entirely defined by "functional programming" + "actor model" is a big part of this. The existence of Dialyzer is a testament to its amenability to automatic analysis.
In terms of a specification, have a look at Elixir's test suite.
A test suite isn't a specification (though it's a lot closer than a tutorial): all computer languages contain infinities (e.g. expressions can be arbitrarily large); test suites cannot express infinities.
And a test suite certainly isn't a reference document. A good language reference document says "here are all the forms of the language, here is what they all mean". The Erlang Reference Manual is a very good example of such a document.
(I'm not trying to be a bear; "There is no language documentation" is a perfectly acceptable answer for me; it just means there is no way for me to discuss the specific benefits Elixir may have.)
> The Erlang Reference Manual is a very good example of such a document.
Erlang has had quite a bit longer to produce such a document, though, hasn't it?
Why bother doing that when you're still fiddling with the language?
In terms of CS friendliness, I get the impression that Haskell is far more popular with that crowd in that it has more things of interest to people doing language hacking. Erlang has "functional" and "actors", but not a lot of other stuff that seems to be of interest to the CS crowd, like types.
> "There is no language documentation" is a perfectly acceptable answer for me; it just means there is no way for me to discuss the specific benefits Elixir may have
No way at all? I think you can tell a lot about a language without some kind of formal documentation.
Why bother doing that when you're still fiddling with the language?
To me, that sounds entirely backward :) I've never implemented a language I haven't already designed "on paper". (Why bother? With a good reference document, you can write and test programs in your head. Implementation is tedious; I only want to do that once.)
In terms of CS friendliness, I get the impression that Haskell is far more popular […]
It is. I don't really know why. Haskell has a lot of libraries and a good compiler, but it's otherwise pretty boring. Its type system is nothing special (OCaml and Mercury have very similar but more interesting systems, notably w/r/t subtyping), monadic I/O is one of the silliest contortions I've seen (uniqueness types in Mercury and Clean are much easier to work with), and laziness isn't all that useful (it is useful but I've never missed not having it).
(I say this with all respect to the Haskell designers: it's a very good language, and they successfully met their self-imposed goal of being fully functional; I just happen to think that that goal led to Haskell being ultimately boring.)
Erlang has "functional" and "actors", but not a lot of other stuff that seems to be of interest to the CS crowd, like types.
That's exactly it. It doesn't have a lot of stuff. The language is incredibly simple, EVERYTHING is explicit, it doesn't encourage first-class metaprogramming, and it ships with its own parser and pretty-printer. That's a CS researcher's dream. That's why Dialyzer (which is better than many, if not most, built-in type systems) can exist. You don't need a built-in type system if your language is simple and analyzable enough to admit a 3rd-party one.
No way at all? I think you can tell a lot about a language without some kind of formal documentation.
Sadly, all I can tell from the tutorial and front page is "Elixir has some kind of metaprogramming that's probably based on Ruby or Javascript". Like I said, I'm a huge fan of metaprogramming done right, but that hinges on lots of specific language details that aren't clearly documented.
Without specifics, any discussion about Elixir's metaprogramming features might as well be a discussion about Javascript's or Ruby's, because that's all I have to go on.
> To me, that sounds entirely backward :) I've never implemented a language I haven't already designed "on paper". (Why bother? With a good reference document, you can write and test programs in your head. Implementation is tedious; I only want to do that once.)
The answer in this case seems likely to be: Jose started fiddling around with it, and at the same time was learning what he could and could not do on Erlang's VM.
I guess I take a favorable view of experimentation and a dimmer view of being able to plan everything ahead of time. At some point in time, things need to be stabilized, but at the beginning, some contact and pushback from the real world and real usage may well impact the design of a system.
> monadic I/O is one of the silliest contortions I've seen (uniqueness types in Mercury and Clean are much easier to work with)
As far as I can see they're all basically the same thing. You enforce sequence by creating a chain of notional "real world" values. I can't say I've used Clean or Mercury extensively, but as far as I can see they just make you pass around that value explicitly. That doesn't really seem like it would be "easier to work with".
> That doesn't really seem like it would be "easier to work with".
1. You dont need monadic versions of all non monadic functions. You dont need fmap, you can just use map.
2. It means there is a well defined order of execution (i.e. The order does not "emerge" as in Haskell, instead it is defined and verified by type system)
It is much much easier to work. In Haskell you feel forcedto separate io from transformation as much as posible. Often you end with either repeating ourself a lot (writing oth mondic as non monadic versions) ir you venture out in monad transformers, which imho is the "goto" of Haskell. (How to turn your code in unreadable unmaintainable spagetti). The cognitive overload is never worth it.
Ps. Uniqueness types are not just about IO. Rust uses them as well. They are about sharing. Haskells needs an IO () type because without a monad it has no defined order of execution, and it cant prevent you from "forking the world" when working with outside references.
If Haskell could prevent you (by using uniqueness) i doubt they would have used monads for IO. (Although they can be usefull in other areas).
> If macros worry you unduly, then Elixir is not for you.
Really? It seems interesting, but I'd simply choose not to use macros in my own code. Seems like they can be avoided in most situations. There's even a heading in the introduction that says 'Don't write macros': http://elixir-lang.org/getting_started/5.html
Macros are more for writing libraries than applications, so certainly what you are saying is correct. However, some people don't like that capability to exist at all - they are afraid it will be abused in code they support or rely on.
2) Dialyzer works fine on Elixir beam files. You can specify type & spec attributes just like in Erlang.
If macros worry you unduly, then Elixir is not for you. I personally prefer to use macros than type lots of boilerplate code, but yes there are some downsides.
edit: Actually I should have said reading and typing - reading boilerplate is much worse than writing it. Judicious use of macros can clarify intent for someone reading the code.