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The future of the Crystal language (crystal-lang.org)
122 points by cylo on Dec 29, 2015 | hide | past | favorite | 36 comments

I don't know it is only me or its apply to others too, My own field is OS and I love it. But recently I am literally fascinated by whats going on in "Programming Language" field. Rust, Go, Nim, Julia, Haskell, Ocaml, Racket, Clojure etc (though these are not scientific research in PL community, but we can claim these are mostly result of scientific research). I wasn't aware of crystal . I literally Love them all and if I were going to an abandoned island for rest of my life , my only wish would have been : "let me play with all of these for rest of my life"

BTW : I looked at crystal syntax (I am talking about only syntax). Syntax designed extremely clear. I would say (my opinion, in short time I had to investigate crystal) maybe clear'er that python.

The real reason they couldn't find anything when Googling the language in the future is because of the inconvenient naming. Every time I search for Crystal, I have to pick out the results from SAP Crystal Reports.

I wish more people took this aspect of their projects seriously. You don't need a short domain name, but your project does at least need to be Googlable.

It's the same with other languages as well: Go, Julia, Ruby (when I searched for some "Ruby Bangkok" meetups, I found thousands of offers to buy real rubies in Thailand. Same with frameworks: Phoenix, Sinatra, Iron, Gin.

After some time Google learns and shows you relevant results, but if you use Startpage or DuckDuckGo, you have to add "lang" or "framework" to search query

C is by far the worst...

Side Note: In DDG Lua doesn't need 'lang', you can type in a function name and it'll give you documentation in the 'instant answers' thing.

Google seems to know that when I am searching for ruby, I want it to rank the programming language first. In due time it will know that by crystal I mean the programming language.

I agree, but I note some of this is out of your control. Rust used to be very clean wrt Google, and then Rust the game was released in 2014.

You can use #crystallang

Search for "crystal language" instead.

If you're a web dev and want to build an API be sure to check out Kemal: http://serdardogruyol.com/kemal/

a Sinatra for Crystal. Wonderful. Now if there is a Sequel equivalent… I'll be sold.

> Note that the above “if” starts with “if instance variables types remain the same”. But how can we know that? The problem is that the compiler determines their

> type by traversing the program, instantiating methods, and checking what gets assigned to them. So we can’t really reuse the cache because we can’t know the final

> types until we type the whole program! It’s a chicken and egg problem."

Maybe I'm oversimplifying it, but suppose you compiled a statement like...


...into something like...

if a is an integer (which would presumably be something fast like "CMP [RAX],123; JNZ NotAnInteger") do "INC [RAX+8]", otherwise do more expensive stuff to look up the actual type and a function to use as a ++ operator?

As long as the programmer sticks to the same type, the compiled expression runs fast, and if they switch types midstream, it still runs, albeit with a performance hit.

You might be interested in deoptimisation: :)


This would have the effect that you describe (actually even faster than what you're proposing, by essentially trapping on all changes to the target to know ahead of time that deoptimisation has to occur), but it's not the world's most trivial feature to implement.

Don't really know Crystal but it seems to me that it is statically compiled which means you need to find the type of 'a' at compile time. The approach you suggest is more commonly used in dynamic languages and involves keeping at runtime a tag on every single value that indicates it's type (memory and speed overhead). You would be trading compile time with run time. Also it seems that not only it is statically compiled, it produces a static binary in the target platform. If, like others suggest in this thread, you were to optimize at runtime instead of generating the alternate paths, you would need a bytecode representation of the program embedded in the executable and very likely a virtual machine with the optimiser and capability to hot reload code. Any of these options would be a substantial departure of the current path the language is taking.

That's what a lot of JIT compilers do. SpiderMonkey for example does type inference in the interpreter (or baseline JIT? what do they use now) and uses that to generate almost exactly what you're describing. If the type inference holds (it usually does, even in dynamic languages) then you get almost native performance.

We mostly want to never have to do this. This way we can guarantee that "no method error" never happens at runtime (one of the most feared exceptions after a big refactor in a dynamically typed language)

Taken from Github on the "why?"

We love Ruby's efficiency for writing code.

We love C's efficiency for running code.

We want the best of both worlds.

We want the compiler to understand what we mean without having to specify types everywhere.

We want full OOP.

So why would I pick Crystal over Scala or F#? Crystal used to be targeted very specifically at Ruby fans; if it's diverging further from Ruby and becoming just another modern typed language, what's its USP compared to the established languages in that space?

neither scala nor f# are c speed.

They're pretty close; I'd be amazed if Crystal were any faster (it's also GCed, right?).

It's probably faster.

I was looking at https://www.techempower.com/benchmarks/#section=data-r11&hw=... today for unrelated reasons. Crystal does better than I'd expected, but less well than Scala (Spray being the comparison I'm interested in since that's what I use); F# doesn't seem to have been tested.

> We want the compiler to understand what we mean without having to specify types everywhere.

If they are looking for complainers about having to specify type on Array and Hash declaration I'll complain... It's seriously one of the problems with Crystal that kept me away. I'd guess some other rubyists are turned off by specifying types.

Specifying types everywhere basically takes Ruby-like syntax and makes it look like Scala or Rust. Why bother with a fully typed Crystal then when similar alternatives have greater support and other advantages?

If we observe how us human communicate, we see a lot of guessing. Human languages are all ambiguous and their great efficiency depend on (intuitive) guesses -- in expensive guesses. We make guesses as we listen/read, but we do not commit our guesses; rather we modify our guesses as we accumulate further information.

Now imagine if we forbid ourselves to modify our guesses, you'll see how understanding natural language a forbidding task ...

Compilation is essentially a guess of meaning with no room for modifications -- neither self-modifications nor post-hoc modifications. So it is doomed for inefficiency or un-trackable difficulties.

I believe the right way for the future of programming is multi-stage compilation -- with first meta-compilation followed with static compilation. Currently our compilation only refers to the latter. The meta compilation produces human readable intermediate result -- not much different from our current code in C or Java and it will be as easy to feedback from as we do today in C or Java. However the meta-compilations takes many guesses and quite often adventurous guesses but the coder can easily tell whether it is on-track or guessed wrong. When the coder detect the meta-compilation guessed wrong, he will simply modify his source code -- slight change styles or simply write the code in a different way (which is not much different from human communication when we say "what I meant was ..."); or, in a few specific or difficult cases, the coder may opt to directly modify the intermediate code (C or Java or any of current popular languages) -- not much different from natural language when we reduce to more specific way as we write laws and contracts.

I have been exploring such idea with MyDef -- a meta programming system -- and have been more convinced it is the more sensible way (than trying to make break-throughs in the mature field of programming languages).

>We love Ruby's efficiency for writing code.

Ruby's syntax is one of the worst parts of Ruby. [0]

>We love C's efficiency for running code.

Many other languages have efficient native code compilers, too. I don't know why people assume this is only a C thing.

>We want the best of both worlds.

>We want the compiler to understand what we mean without having to specify types everywhere.

This is good. I much prefer dynamic languages to static ones. Though I don't know if Crystal supports the best parts of dynamic languages like runtime program modification AKA live coding.

>We want full OOP.

Single paradigm languages feel very restrictive to me. I like languages that support many paradigms because different parts of programs call for different programming techniques. OOP in particular is a paradigm that I feel forced to use more often than I feel it's the right technique for the task at hand.

[0] http://programmingisterrible.com/post/42432568185/how-to-par...

> Many other languages have efficient native code compilers, too. I don't know why people assume this is only a C thing.

I think it's just become very common to show C as the reference to show how fast are other programming languages, and everyone keeps it this way.

> Ruby's syntax is one of the worst parts of Ruby. [0]

For people who write the language, yes, it's incredibly hard to parse (and that blog post doesn't mention the new ambiguous things like keywords vs. hashes)

Yet, for people who use Ruby, it's very convenient and easy to read.

I write Ruby for money, and I find it difficult to read and write in certain circumstances. Sometimes Ruby thinks the curly braces mean a hash, sometimes Ruby thinks they mean a lambda. The ambiguities in the syntax (wow, it's just like natural languages!) really drive me crazy.

After learning a variety of programming languages, I think homoiconic syntax is the only type I actually like.

People used to find Perl convenient and easy to read too.

> Similarly, distinguishing puts ([1]).map {|x| x+1} from puts([1]).map {|x| x+1} is handled by setting flags after skipping whitespace, and later checking these flags to emit an LPAREN or an LPAREN_ARG token. As well as semantic whitespace, flags are used for blocks, class definitions and method names too.

What the actual fuck.

What the actual fuck.

That's not particularly unusual, is it?

Significant whitespace, except to separate tokens, is unusual. Significant whitespace that is used for something other than delineating blocks is extremely unusual.

The question is not whether the language has a native code compiler, as that rarely has a profound effect on the runtime speed of a language. Some native code languages are slower than VM and interpreted languages. And native code != native code. Objective-C and Swift both have native code compilers. But they are slower than C and C++ on the same platforms, for various reasons, such as: the runtime environment itself and how the runtime works, and, in the case of Swift, the organization of its LLVM code prior to final compilation.

>>We love Ruby's efficiency for writing code.

>Ruby's syntax is one of the worst parts of Ruby. [0]

Your reference is about parsing the syntax, I am certain the authors mean they want Ruby syntax from the coders perspective not from the parsers perspective.

Humans have to parse the syntax as well...

Nearly all the syntax ambiguities I've had in Ruby were resolved by either adjusting some whitespace or adding parens, and neither make the code any more difficult to read. In my experience Ruby is easy enough for humans to parse (really nice in 95% of cases, weird in 4%, WTF IS HAPPENING in 1%).

That's not really the context for the reference. Also beauty is in the eye of the beholder. The Crystal authors aren't really debating the goodness of Ruby syntax... That they think it's good is kind of the precondition to Crystal existing.

If I had to optimize parts of a ruby project, I think it would be much better to port the code to crystal than C or Go.

Only just had a quick peep and play and I like it - looking forward to using Crystal more often on a tooling level.

Nice work to date...

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