Felix - a fast scripting language

http://felix-lang.org

by nmcfarl • 14 years ago

107 83 14 years ago

felix-lang.org

nmcfarl2• 14 years ago

This is interesting, but the home page is the most coherent and readable on the site. Better resources look to be:

The Facebook group: http://www.facebook.com/groups/243958412369802/

And google group: https://groups.google.com/forum/?fromgroups#!forum/felix-lan...

srean2• 14 years ago

@nmcfarl thanks for resubmitting with a different url. I find the home page a bit baity but the tutorial page http://felix-lang.org/web/tutorial.fdoc is great.

Depending on how you look, it is C++ speed OCaML, or perhaps more correctly C++ in a fully type-inferred (unfortunately, nowadays almost everything gets called type-inferred. Hence the added qualification "fully"), ML like language.

It does whole program optimization. It uses a mix of lazy and eager evaluation strategies for speed.

I believe it can generate Python modules too, thanks to how well it interacts with C. The details have to be gleaned from the mailing list though.

nmcfarl2• 14 years ago

I was actually using submissions as a poor man’s substitute for HN search :)

I found the tutorial ( http://felix-lang.org/web/tutorial.fdoc ) to be a bit info sparse when I had no clue what I was looking at. Once I’d poked a round a bit it was much better, and started answering questions I was having - mainly how FFI is handled: http://felix-lang.org/web/nutut/intro/intro_01.fdoc

A very cool project.

asimjalis2• 14 years ago

Out of curiosity: How did you generate the slides?

Yttrill16• 14 years ago

The webserver, which is written in Felix, translates a particular format called "fdoc" to create the tutorial and slides, including embedded colourised hyperlinked Felix and C++ code. The translation is to a mix of HTML5 and Javascript. This link shows the source of the first slideshow:

http://felix-lang.org/web/slides/language-overview.fdoc?text

All the documentation and layout needs a lot more work. [BTW: I'm the primary developer]

bdcravens• 14 years ago

All the documentation and layout needs a lot more work.

Yes, clicking links to get a small page of content to only find another link to click .. gets old really fast. (Old as in it feels like the Java documentation circa 2001)

cpeterso2• 14 years ago

Yttrill, I see that Felix is 12+ years old. I remember reading about Felix on Lambda the Ultimate a few years ago. :)

Over those 12 years, what are some of the biggest changes (in the language or its implementation) you have made? Where the changes mostly evolutionary?

https://github.com/felix-lang/felix/commits/master?page=135

Toshio2• 14 years ago

Love at first sight, but the build script is broken.

http://pastebin.com/raw.php?i=WzB5Jqyf

Yttrill16• 14 years ago

It works with this:

~/felix>python3 Python 3.2.3 (v3.2.3:3d0686d90f55, Apr 10 2012, 11:25:50) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin

and also on Linux with this:

skaller@felix:~$ python3 Python 3.2.3 (default, Oct 19 2012, 20:10:41) [GCC 4.6.3] on linux2

I have been told that the script fails if you use a slightly different version of Python:

  File "/usr/lib/python3.3/subprocess.py", line 906, in communicate

So it is an incompatibility in Python 3.3 subprocess module I think.

Toshio2• 14 years ago

Indeed, I tried it on a fully up-to-date installation of ArchLinux.

mrcharles• 14 years ago

I'll stick with Lua. I wouldn't give up the dynamic aspects of a language like Lua just for a bit more speed. LuaJIT is more than enough, and if you are doing the hard number crunching that makes speed an issue there's a good chance it's not trivially harder just to write it in C++ to begin with.

dkersten2• 14 years ago

For raw number crunching, LuaJIT is plenty fast anyway (when you use the FFI to instantiate native types), so unless you need something real special (SSE perhaps), it may not even buy you that much to use C++ over LuaJIT.

iskander• 14 years ago

Just a small clarificatation: the 2.x version of LuaJIT only compiles floating point operations to SSE2 (http://lua-users.org/lists/lua-l/2010-03/msg00142.html). I'm not sure, however, whether it does vectorization or just operates on one float at a time.

jheriko• 14 years ago

See fridgescript (http://code.google.com/p/fridgescript/) - because you are going through C/C++ it is faster in its domain (x87 floating point work) if given good clean code. Its not big or clever - just that C/C++ kills its performance a little with restrictions like struct layout rules and standard library math functions being rubbish... (note the compiler uses almost no optimisation strategies and the language is very specific and almost useless though)

That being said, I like the idea very much, I just object to the claim of fastest and the value the claim implies. Beating C is very easy if you know some very basic things about the restrictions placed on it by standards... :)

PuerkitoBio• 14 years ago

Looks very interesting, well done to whoever did this. After an admittedly quick and superficial glance at the tutorial, I'm not fan of chapter 6 though. Why so many ways to write calls? With no idiomatic syntax, it means I have to know all these variations if I hope to understand Felix code (since it is ok for anyone to choose whichever style).

andrewflnr6• 14 years ago

I just don't understand why there are both gen and proc functions. Why have a separate kind of thing for functions that don't return anything?

egonschiele• 14 years ago

Functions aren't supposed to have side effects and procs are. It makes sense since functions without side effects would allow for some nice compiler optimizations. The part that scares me is that the compiler doesn't enforce no side effects. This means you need to be extra careful when using someone else's code.

raphinou• 14 years ago

I've kept an eye on felix-lang the last several months, and the project seems to be progressing continuously.

I'm curious though: has it been used in production? I'd be very interested in reading real use stories, with up and down sides!

Also, how is the community doing, and what about contributors? Do both groups grow?

zem2• 14 years ago

i've been keeping a vaguely interested eye on it for years, because it does look interesting. it has failed to make it to the front of my "learn this language next" priority queue due to the fact that i can't find anyone using it for anything, not even a hobby project on github. also, the documentation is a bit sparse.

one killer feature that would make me start learning it immediately is good, well-documented qt bindings (i'm sure it is possible, since felix compiles down to c++, but with the sparse documentation i have no idea how i would go about getting it up and running, and insufficient motivation to first learn the language and then figure out how to do it).

hipjiveguy• 14 years ago

how does this compare with haXe (haxe.org)?

I see that it's billed as a "C++ code generator" and as a "scripting engine".... Does it generate C++ code that I could use without Felix afterwards?

Yttrill16• 14 years ago

Yes, provided you collect all the required library headers and either sources or binaries: the generated C++ still requires run time libraries and the top level driver if it's a program.

There is actually an option of flx, --bundle=dirname, which puts the generated C++ in a single directory, to make it simpler to ship the generated C++ to another platform.

This does not do a full bundle, i.e. it doesn't package all the run time support code as well. That's on the TODO list, so you could literally copy the target directory to another machine and run "make" or something and only need a C++ compiler to build it.

There's another aspect to your question: if by "use" you also mean "modify" then the current state is that Felix generated C++ is a bit hard to read. The code is "good enough" to add debugging prints but not much more. It would be good to improve this so the code is more readable.

haberman6• 14 years ago

The web page rubs me the wrong way. How can you claim to be the fastest anything without a single benchmark? How can you claim to be a "scripting language" when you're statically-typed and compile to C++? What does "scripting language" even mean then? How can you say things like "it will be a bit slow the first time but subsequent runs will load much faster than any VM." Any VM? Are you really "much faster" than:

  $ time lua empty.lua 

  real	0m0.005s
  user	0m0.002s
  sys	0m0.002s

  $ time ./luajit empty.lua 

  real	0m0.005s
  user	0m0.001s
  sys	0m0.002s

Maybe there's cool stuff going on here but I can't get past being annoyed at these over-hyped claims.

aaronblohowiak2• 14 years ago

My "good enough" definition: a scripting language is a language that does not require you to write a main() function or define a class / object in order to produce output and features automatic memory management.

chc• 14 years ago

So Common Lisp and Fortran are scripting languages? This test seems to be more like "Is the language heavily influenced by C or C++?"

dkersten2• 14 years ago

Indeed. In my experience, LuaJIT is insanely fast and is widely considered to be one of the fastest dynamic languages around. The term "scripting language" is, in my opinion, meaningless these days, but either way, claiming to be as faster than LuaJIT and aiming to be faster than C (while compiling to C++? [1]) and not demonstrating this to be true just seems pretentious.

[1] I guess it should be faster than hand-written C, which is, of course, possible. ATS supposedly generates C code which is very competitive.

zem2• 14 years ago

are you referring to the "The fastest scripting language on Earth" tagline? i saw that as a way to say "look, this is a compiled language that you can use as a scripting language" with a touch of whimsical humour.

haberman6• 14 years ago

Interesting. If that's the way it is intended I missed it completely; I'd definitely be much more receptive to that line of meaning.

Yttrill16• 14 years ago

Did I mention Felix is based on Cat-e-gory theory and named for the inventor of one-sided donuts?

srean2• 14 years ago

This was pretty much exactly my reading.

Yttrill16• 14 years ago

Macbook Pro:

  ~/felix>flx --test=build/release --static mt
  ~/felix>time ./mt

  real	0m0.004s
  user	0m0.001s
  sys	0m0.002s

  ~/felix>time ../lua-5.2.1/src/lua mt.lua

  real	0m0.006s
  user	0m0.001s
  sys	0m0.003s

aDevilInMe• 14 years ago

What are the LuaJIT timings on the same machine also is this the proof that it is "The fastest scripting language on Earth."? Please provide your profiling results with the languages tested, the files ran and the timings.

d0m• 14 years ago

At first glance, it seems fairly complex. For instance, 4 different kinds of variables, 3 different kinds of function. But I guess that's understandable if it compiles to C++ and is looking to be highly efficient.

mitchi3• 14 years ago

Which high level optimisations are we talking about?

Yttrill16• 14 years ago

As a whole program analyser, Felix does a lot of optimisations. The most important one is inlining. Felix pretty much inlines everything :)

When a function is inlined, there are two things you can do with the arguments: assign them to variables representing the parameters (eager evaluation) or just replace the parameters in the code with the arguments (lazy evaluation).

Substitution doesn't just apply to functions: a sequence of straight line code with assignments can be converted into an expression by replacing occurrences of the variables with the initialising expressions.

For a small number of uses, substitution is the usually the most efficient. For many uses, lifting the common expressions to a variable is more efficient. If we're dealing with a function (in C++ the model is a class) for which a closure is formed (in C++ the model is an object of the class) lazy evaluation is very expensive because the argument itself must be wrapped in an object to delay evaluation.

By default, Felix val's and function arguments use indeterminate evaluation semantics, meaning the compiler gets to choose the strategy. This leads to high performance, but it also means we need a way to enforce a particular strategy: for example vars and var parameters always trigger eager evaluation. This leads to some complication in the language.

Felix also does other optimisations, for example it does the usual self-tail call optimisation. This one works best if you do inlining at the right point to convert a non-self tail call (which cannot be represented for functions in C) into a self-tail call (which is replaced by a goto).

Felix also does parallel assignment optimisation.

It ensures type-classes have zero cost (unlike Haskell which, by supporting separate compilation, may have to pass dictionaries around).

There is quite a lot more: eliminating useless variables, functions, unused arguments, etc. There are even user specified optimisations based on semantics, such as

  reduce idem[T]  (x:list[T]) : list[T] = x.rev.rev => x;

which says reversing a list twice leaves the original list, so just get rid of these two calls.

Actually one important aspect to the optimisation process: by default a function is a C++ class with an apply() method. This allows forming a closure (object). The object is usually allocated on the heap. However Felix "knows" when it can get away with allocating such an object on the machine stack instead (saving a malloc and garbage collection). Furthermore, Felix "knows" when it can get away with a plain old C function, and generates one of those instead if it can. And all of that occurs only if the function wasn't entirely eliminated by inlining all the calls.

So although you should think of Felix functions and procedures as objects of C++ classes allocated on the heap and garbage collected, any significant program implemented with this model without optimisations would just drop dead.

mitchi3• 14 years ago

These are very good optimisations indeed. Inlining adds a lot more speed than people think. I don't understand why people want closures in their languages. You basically want a function that cheats her own scope... I don't get where the big deal is.

TylerE3• 14 years ago

Why do language designers continue to insist on semi-colon terminated lines?

reinhardt• 14 years ago

Perhaps to dissuade the lowest common denominator of programmers that get hung up on such superficial trivialities.

TylerE3• 14 years ago

But it's not triviality - it's noise - Signal: Good - Noise: Bad, got it?

If you REALLY need end of line markers, any half-way competent text editor can display them for you.

munificent2• 14 years ago

It's simpler to parse and some programmers prefer them.

Someone• 14 years ago

And simpler to parse has another benefit Given an effort X spent writing the parser, users of the language get better error messages

Also, I do not think of those semicolons as noise They make text easier to parse for humans, too That's why you see most people end sentences, paragraphs and HN posts with a 'superfluous' period

EDIT: Some people will find the above quite readable I am somewhat in that camp Problem is, however, that in English and other languages capitals like I and E are not guaranteed to be sentence starters That muddles the waters considerably Many programming languages have worse problems.

Yttrill16• 14 years ago

Two choices dictate a terminator: (a) free form 1D language like C vs 2D language like Python or Haskell, and, (b) support for assignment statements x = y and the like as in C vs all statements starting with a keyword as in say ATS. I personally do not like the semi-colons either.

TylerE3• 14 years ago

Doesn't even need to be 2D Layout. See, for instance, ruby.

watmough• 14 years ago

They are smoking crack if they think anyone will use a scripting language that doesn't have a functioning REPL.

My goto-languages for quick development are Perl 5, Clojure and Javascript.

All 3 are adequately fast for real tasks. All are cross-platform, and all 3 support a REPL that allows doing real work interactively.

These conditions are the absolute minimum to be viable as a scripting or sketch/prototyping language.

asimjalis2• 14 years ago

What REPL do you use for Perl?

aflott• 14 years ago

The most bare bones is: 'perl -de 0' CPAN has a few others

prakashk• 14 years ago

As aflott does, I use the built-in debugger as REPL for most simple uses.

I also use re.pl from Devel::REPL (https://metacpan.org/module/Devel::REPL).

Yttrill16• 14 years ago

There is an alternative: a quick start GUI mini-IDE which allows you to type in and edit the code and press a button to run it. Such tools are mandatory on Windows anyhow: Ocaml and Python both have this for example. Most Unix editors like Vim or Emacs could be programmed to do this fairly easily I guess. I even wrote such a tool once using Tcl/Tk.

I agree this is not the same as a REPL with line by line interactive execution/editing with an environment that saves well defined symbols. Ultimately this would be tough to see through because Felix binds functions statically and lookup is setwise (like function scope in C) not linear, so recursive definitions cannot be introduced one at a time.

rz2k• 14 years ago

This isn't very difficult to configure in Sublime Text 2 for different languages.

andrewflnr6• 14 years ago

I like the array type syntax: an array of five ints is

  int*int*int*int*int === int^5

instead of something like int[5]. Lots of interesting little ideas.

jaipilot747• 14 years ago

How is

    int*int*int*int*int

or even

    int^5

better than a plain int[5]? To me, the use of mathematical operators * and ^ causes dissonance.

munificent2• 14 years ago

If you're coming from a type theory background (which, granted, few are), this operator is actually perfectly natural.

http://en.wikipedia.org/wiki/Product_type

michaelfeathers• 14 years ago

While I enjoy reading about new and interesting languages (note: Felix has been around for over ten years), I really wish that language designers would put example code for something like FizzBuzz right on the front page to give people a flavor of the syntax.

I can't remember how many times in my life I've done a link expedition through a website or docs just to see a simple programming example.

Yttrill16• 14 years ago

  for var i in 1 upto 15 do 
    println$ 
      match i % 3, i % 5 with
      | 0,0 => "Fizz-Buzz"
      | 0,_ => "Fizz"
      | _,0 => "Buzz"
      | _ => str i
      endmatch
    ;  
  done

Did I get the job?

eriksank2• 14 years ago

I find it definitely a nice language proposal, but there are a few issues, I guess. A first one is that many of the distinctions introduced (such as proc,fun,gen) are all optimization issues. I would appreciate if it were possible to do that long after you're done with just making the program work. The language may force the developer way too early in the process to think of things that do not matter at that point. In the best case, it will matter later on, when the program truly works. Another issue I have is that the "simplifications" introduced initially lead to introducing lots and lots of additional symbols such $ and #, just because the simplification was apparently not leading to something simple. So, the language suffers from enforcing a premature optimization mindframe as well as from overly complex administrative simplification.

Yttrill16• 14 years ago

The proc/gen/fun distinction isn't entirely an optimisation issue, its a semantic one, heavily related to the implementation model. In principle fun and gen use the machine stack for return addresses whilst proc uses a heap allocated list which allows cooperative multi-tasking using channels for communication: such so-called spaghetti stacks are easy to swap. Machine stacks can only be swapped in a conforming way in C/C++ by using pre-emptive threads which is precisely what we're trying to avoid.

I said "entirely" above because semantics and optimisation are heavily intertwined in any system.

The comment about "syntactic sugar" is valid: there are at least four operators with different precedences all meaning "application of function to arguments". However note that in most languages this is true anyhow: x + y is really just add (x,y). Finding a good set of squiggles and marks that's acceptable to many people isn't easy.

However the syntax is defined in the library, in user space, so you can add your own grammar or design your own domain specific sub-language, and add your favorite squiggles that way. Any contributions to making the standard syntax simpler would be welcome: I'm constantly struggling with this issue because I'm well aware syntax matters, especially early in learning a language.

eriksank2• 14 years ago

I have created a blog post explaining why I think the language has too many problems to ever take off: http://erik-poupaert.blogspot.com/2013/01/the-felix-programm...

Felix - a fast scripting language

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