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The Julia Programming Language

julialang.org

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Re: The Julia Programming Language

#81

Post by ViralBShah »

fijal wrote: post #39
mjw wrote: post #26

I wonder what they think about or have learned from http://en.wikipedia.org/wiki/Fortress_(programming_language) , another recent-ish attempt to deliver a modern and powerful scientific programming language. Personally I'm a little wary of being ghettoised into something overly domain-specific for scientific/numerical computing. Really good interop may mitigate that -- something which can navigate the unholy mix of C…

Python+numpy+scipy does work only if you actually don't write much python or at least not run much python. Otherwise it sucks

I wouldn't say that it sucks - that's way too strong. I am one of the authors of Circuitscape (http://www.circuitscape.org), which uses python+numpy+scipy. The community loves it, the fact that its python, open source, embeddable in other tools, etc.

However, much of the code is written in a vectorized style for performance reasons, as is the case with many high level scientific computing languages. This leads to unnatural code in some cases, and also uses too much memory. First I thought IronPython was the way, but have been looking forward to pypy+numpy+scipy eagerly.

If I were to use julia, the code would be a lot more natural, because type inference and all the compiler goodies make it possible to simply write loops over arrays when I need them. This was one of the reasons we started working on julia, because everything else just seemed to fall just a little bit short.

Re: The Julia Programming Language

#82

Post by wes-exp »

StefanKarpinski wrote: post #73
tomp wrote: post #59

Earlier quoted context omitted.

What else would you suggest? I find that the @ syntax is amazing, since the reader (programmer) knows exactly which form is a macro (and can look it up), as opposed to introducing arbitrary, often very confusing syntax.

Thanks. We've considered doing other things — like function call syntax for macros (which is essentially what Lisp/Scheme have), but decided against it. It just causes confusion. Can you pass a macro around like you can a function? Can functions shadow macros and vice versa? What happens if a macro introduces a local variable that shadows the macro itself? Basically it comes down to fact that macros are syntactic and…

Seems like there have been a variety of attempts to introduce lisp-style macros into non-lisp languages that use traditional syntax rather than s-expressions. I can see how this can succeed for simple macros without sacrificing much. However, complex macros done this way tend to be much more complicated than the equivalent lisp code. Do you believe that Julia solves this problem, or is it also subject to some of the same tradeoffs?

Re: The Julia Programming Language

#83

Post by ViralBShah »

muuh-gnu wrote: post #75
StefanKarpinski wrote: post #67

Earlier quoted context omitted.

Yeah, we've been waiting for a while for Fortress too. It seems like a lot of time and effort has gone into a WYSIWYG IDE and not as much into the actual language implementation :-( Chapel has made a lot of progress in the past 2.5 years (while we've been working on Julia) and is certainly a contender. Julia certainly aims to be more dynamic like Clojure, but specially designed to be good for numerical and technical…

> he begin/end is due to Matlab Octave has solved this by allowing both matlab-style "end", as well as block-specific endings, like "endif", "endfunction", "endfor", etc. Having several end end end endings without any hint of what they are closing is one of the ugliest parts of matlab. Even though you are reimplementing this for compatibility reasons, it is rather sad that you chose to make this the default behaviour…

The language is still quite young and is certainly going to mature. Also, it is open source. So, please do not lose heart, not just yet. :-)

Re: The Julia Programming Language

#84

Post by andrewcooke »

StefanKarpinski wrote: post #78
andrewcooke wrote: post #30

this is surprisingly complete for a relatively new(?) project. one notable restriction is that inheritance is only for interface, not implementation. also, can anyone find a sequence abstraction (like lists)? arrays seem to be fixed size and i don't see anything else apart from coroutines. am i missing something?! [perhaps not, if it's intended for numerical work. on reflection i am moving more and more towards gener…

pron is right: you can inherit behavior from abstract types and abstract types, unlike interfaces, can have code written to them. (In single-dispatch OO languages, you are in the strange situation that you can write code to interfaces if they are arguments but not if they are the receiver of a method; thus, you're in a situation where you can either dispatch on an interface or you can write code for it, but never bot…

thanks guys.

Re: The Julia Programming Language

#85

Post by ViralBShah »

mjcohenw wrote: post #80

I am currently building it - OS X Lion. First, I had to install wget:) Then, I got a certificate error on the https, so I pasted the command into Firefox and got the tarball. After copying it to the julia dir, I edited the tar command and ran it. Finally, doing make right now. Here is the certificate error: Connecting to github.com (github.com)|207.97.227.239|:443... connected. ERROR: The certificate of `github.com'…

We used to use curl until recently so that it would build just fine on OS X. We changed it to wget, because it just seems so much easier to use than curl, and we had to do some nasty stuff at one point to download a few libraries that I couldn't figure out how to do with curl.

BTW, do try out the mac binaries if the build is an issue. We are still trying to make it all build seamlessly!

Re: The Julia Programming Language

#86

Post by wbhart »

StefanKarpinski wrote: post #64
wbhart wrote: post #28

Much praise!! These guys have incredibly good taste. Almost every single thing I can think of that I want in a programming language, they have it. All in the one language! The fact that it has parametric types, parametric polymorphism, macros, performance almost as good as C, good C/Fortran interop, 64 bit integers and an interactive REPL all in the one language just blows my mind. I wasn't able to tell if it is poss…

Thanks for the incredibly high praise. It definitely is possible to overload operators — operators are just functions with special syntax (see http://julialang.org/manual/functions/#Operators+Are+Functio... ). We don't have bignum support, but adding it via GMP would be fairly easy. Just too many things to do!

Great news about the operators. I didn't see an example of overloading there, but I probably rushed through it a bit quickly.

I have been working on and off on a BSD licensed bignum library. Maybe in a few years....

Re: The Julia Programming Language

#87

Post by wbhart »

StefanKarpinski wrote: post #74
ludwigvan wrote: post #56

Earlier quoted context omitted.

Actually, broadly speaking, I think math (think summation etc.) in general is usually 1-index based while programming is 0-index (due to memory locations so that the array index also points to the first element?). Also see Dijkstra's take on the matter: http://www.cs.utexas.edu/users/EWD/ewd08xx/EWD831.PDF for

At first we were going to use 0-based indexing, but it made porting any Matlab code over very hard, which defeats a large part of the purpose of having Matlab-like syntax in the first place — to leverage the large amount of Matlab code and expertise that exists out there. However, as I've used it more and more, 1-based indexing has really grown on me. I feel like I make far fewer off-by-one errors and actually hardly…

Many divide-and-conquer algorithms seem to be easier to express with 0 based indexing, whereas quite a few array operations seem to be better with 1 based indexing. I can certainly understand and appreciate the different points of view, I just personally always think about algorithms with 0-based arrays.

Re: The Julia Programming Language

#88

Post by ViralBShah »

wbhart wrote: post #33
ludwigvan wrote: post #29

Earlier quoted context omitted.

I think they are aiming for smooth transition for MATLAB users. They also have 1-index based arrays as opposed to 0-index .

It would certainly be nice if there was an option to use 0 based indices in blocks of code. It's understandable in that they are pitching at the technical community, and many mathematical papers and books are written with 1 based indices. But I am a mathematician who prefers 0 based indices.

Actually, it is quite easy to implement 0 based indices or any other indexing scheme in julia, since all the array indexing code is implemented in julia itself.

https://github.com/JuliaLang/julia/blob/master/j/array.j#L15...

I personally would find multiple indexing schemes confusing both for usage as well as to develop and maintain. Given that 1 based indexing seems to be a popular choice among many similar languages, we just went ahead with that.

Re: The Julia Programming Language

#90

Post by tomp »

StefanKarpinski wrote: post #73
tomp wrote: post #59

Earlier quoted context omitted.

What else would you suggest? I find that the @ syntax is amazing, since the reader (programmer) knows exactly which form is a macro (and can look it up), as opposed to introducing arbitrary, often very confusing syntax.

Thanks. We've considered doing other things — like function call syntax for macros (which is essentially what Lisp/Scheme have), but decided against it. It just causes confusion. Can you pass a macro around like you can a function? Can functions shadow macros and vice versa? What happens if a macro introduces a local variable that shadows the macro itself? Basically it comes down to fact that macros are syntactic and…

Just a comment/suggestion: could someone with GitHub write access go over your wiki and fix code samples where multiple lines have been concatenated into a single line? E.g. https://github.com/JuliaLang/julia/wiki/Types-and-their-repr..., heading `Built-in types`.
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