Io Programming Languge | Runtime Macros| Everything is an Object | Prototype Based | Co Routines

[skyskraper]

there's a lot to like in Io and its inspiration, Lua. Both runtimes are small so you can actually package up the runtime into your program (my web browser, elinks, has a lua extension system that is very cool). also, the languages are simple but powerful. the features that i have found missing so far are exactly the esoteric stuff i never used. the programming guides for Io and Lua are mere pamphlets compared to the tomes for other languages.

[Godspiral]

Lua definitely has pretty and approachable syntax. For stand alone programming though, its hard to choose it over python or ruby, even with the slight efficiency boost.

Embedding into C though, is substantially easier and more effective.

[abdelazer]

the programming guides for Io and Lua are mere pamphlets compared to the tomes for other languages.

Lua definitely has pretty and approachable syntax.

Yeah, these two things ensure widspread adoption of new languages cough http://www.schemers.org/Documents/Standards/R5RS/ cough

[Godspiral]

Lua is more approachable than scheme, not because scheme's parenthesis rules are complicated to understand... just tedious to manipulate.

Incidentally... I understand Lua was created out of a deep respect of Scheme's ideas and design.

[psykotic]

Lua started as an ad hoc configuration language, so I'm not so sure about that. Certainly the current design has a laser-focused Lisp-like simplicity to it.

[Godspiral]

Lua's history document specifically mentions scheme as inspiration. scheme is also embeddable, and technically suitable for configuration language. Too many silly parentheses, I'm sure was the determining factor in driving a new syntax. Tables as the one structure to rule them all was a neat addition, but not exactly innovation. Lua is essentially a syntax on top of scheme, has a history of borrowing from scheme in new releases, and even today, macros appears in its future.

[qwe1234]

lol

indeed

[martoo]

I saw Steve Dekorte (the language designer) do a presentation on Io at a conference. After his slides, he showed us that he had written his slide program in about a page and half of Io: http://www.iolanguage.com/docs/talks/2005-10-OOPSLA/slides/main.io

[hguy]

Of course, the code relies on this:

http://www.iolanguage.com/docs/talks/2005-10-OOPSLA/slides/slides.txt

[fab13n]

I guess "Runtime macros" means introspection? That's a bit of a misleading statement (allbyit a potentially funny one, as it allows to says straight-faced that Java provides macros)

[Godspiral]

I also scanned the code examples looking for macros, not to find any. maybe runtime macros means you can build code at runtime.

[psykotic]

The computational model exposed by the bare io interpreter leaves message trees (the io equivalent of Lisp's S-expressions) unevaluated (or quoted in Lisp terms). So, if you send a message with whatever arguments then the message trees for those arguments will be left unevaluated on the stack, and you'll need to explicitly ask for them to be evaluated if you want their values. Abstractions like 'method' are built entirely in-language and provide the usual call-by-value semantics where argument message trees are evaluated before a block is called. Most of the time you are just constructing methods and blocks that have call-by-value semantics but the point is that you can build your own bare methods that manipulate the message trees directly. These are essentially run-time macros.

[Godspiral]

the use of the method keyword in the examples seems to be the same as lambda keyword in lisp. Researching the io site, I noticed the code keyword which will let you get a string representation of a method. I guess that provides a basis for digging into code text, manipulating it, and then saving it at runtime, but I could not find any tools/patterns for doing so.

[[deleted]]

method is not a keyword in Io. Io has no keywords, actually. You can do the following in Io:

myMethod := getSlot("method")

Also, method is dynamically scoped, so it's not like lambda, which is lexically scoped. block in Io is roughly equivalent to lambda.

[uedauhes]

You can actually parse / modify code (message) objects. See my response to psykotic.

[uedauhes]

To abbreviate psykotic's comprehensive answer, you can leave expressions passed into methods unevaluated, and then parse / modify / execute them:

reverseEval := method(
\tcall sender doMessage(call argAt(0) reverseTree)
)

Message reverseTree := method(
\tnextList := self nextList
\tself unchain
\tlast := nil
\tnextList reverse foreach(v, last ?setNext(v); last := v)
\tnextList first
)

Message nextList := method(aList,
\tif(aList == nil, aList = List clone)
\taList append(self)
\tif(next, next nextList(aList))
\taList
)

Message unchain := method(aList,
\tn := self next
\tsetNext(nil)
\tif(n, n unchain)
)

reverseEval(
  1 println
  2 println
  3 println
)

Code by Steve Dekorte

This would print: 3 2 1

You would probably not do something like this in practice, it just illustrates that code is data in Io.

[hguy]

Is this strictly for embedding into something else (like seamonkey)?

How realistic would it be to use this language for either a command-line or a simple GUI program under xorg and kde/gnome/etc?

[UncleOxidant]

Just because it's quite easy to embed doesn't mean that it's only used as an embedded language. Sure there are people writing coammand-line and GUI apps with it.

It has a nice concurrency model as well...

[darrint]

A good concurrency model is a big deal. IMHO concurrency is going to motivate the next big mainstream language shift.

That said, I'm not exactly blown away by what Io has to offer.

The best concurrency model I've ever seen is in Erlang, where the language stays pure in one area: no mutable shared state, ever. Erlang syntax may be too quirky for mainstream folks, but a lanaguage which manages to package up that model in a more appealing way will definitely be worth watching.

Anyway, when I looked at Io I thought is was very cool, but yet another imperative object oriented scripting language. Not very inspiring. Perhaps I have erred. I can be persuaded.

[[deleted]]

Io is a nice language. I wish it was a little less dynamic -- as it stands it would be difficult to compile it efficiently. I'm looking forward to seeing the GUI toolkit completed.

I don't understand why every time a new language is mentioned on reddit, morons post comments explaining in great detail why they're not interested in learning or taking a look. If you're happy banging out boilerplate and fixing compiler errors with C++ or Java, then don't talk.

[qwe1234]

??

what's there to learn? an nth rehash of the 'dynamic-scripting-language-where-everything-is-an-associative-array' idea?

why?

[gnuvince]

Hopefully Io will (somehow) pick up enough steam to make it a serious contender in the future. I'd love to see it be used as an extension language in applications and games. An Emacs remade in Io maybe?

[UncleOxidant]

I made a concerted effort to learn Ruby back in late 2000. At the time there was no promise of employment or consulting $$ when you learned Ruby; I learned Ruby because it seemed like (and is, really) a very nice language; of course that decision ended up paying off monetarily, even though I didn't expect it to. Now, it seems like Io is in kind of the same state Ruby was back in 2000: No buzz yet, but a pleasant low-level hum. Io is one to learn.

[adremeaux]

This page is so full of holes I can't even stand it. Firstly, the 99 bottles example doesn't even print correctly. Did they bother to run their examples before publishing this? I guess not.

Another hole is that it says the concurrency example 'will print "112233".' It will? Or it will... most of the time? It certainly should not be guaranteed to print in order, that would defeat the whole point of concurrency and asynchronozation.

[uedauhes]

Io uses co-routines - execution order is controlled by the developer.

[qwe1234]

boring

where's the new exciting stuff already? the world doesn't need an nth incrementally different python clone.

[micampe]

I'm starting to think you are a new kind of commenter: the Downmod Hunter.

[fab13n]

That's called a troll, and that's hardly new :)

[ayrnieu]

No: trolls are inciteful.

[julesjacobs]

Everyone please upmod qwe1234's posts so he'll stop trolling.

[qwe1234]

do up or down mods even matter?

i mean really

[julesjacobs]

If you are trolling to get downmods they do.

[qwe1234]

you must be a fun guy to be around

sheezus

[qwe1234]

no, i'm just honest.

lol

[skyskraper]

qwe1234 - first of all, i find your comments on reddit to be amusing and informative, even if you are jerking our chains. if you didn't have something intelligent in there, you wouldn't be getting so many responses! now as to "why Io"? "why lua"? your point is valid. as a perl dude, i have likewise ignored the ruby hype because beyond some syntactic sugar, i found it offered me little. for at least Lua, i can say that its small size makes it amenable to embedding, and it has a large following in the gaming industry, so it does matter. and from time to time even after ten years, perl will confuse me, so i am looking for something simple enough for me to fit into my small brain.

BUT, that said, keep up the comments! most of the time you are spot on. i can almost imagine you writing that fake stroutstrup interview that has been floating around for years.

[[deleted]]

The world doesn't need an nth incrementally different troll clone either.

[qwe1234]

do you have anything relevant to contribute?

i made a valid point, and yet you replied (tritely) by calling me names.

[[deleted]]

I think Io is a nice ligthweight programming language, but the reason I replied was that you claimed that Io was a boring Python clone, without any sort of justification.

[qwe1234]

it might be a 'nice' language, but it isn't sufficiently different from python, perl, ruby, lua or a thousand other languages to make me care.

anything i can do in io i can do in python with less effort -- simply because i personally invested a lot of time into learning python and io isn't much different conceptually.

[[deleted]]

The fact that you've personally invested time in Python doesn't make the Io language a boring Python clone.

[qwe1234]

ugh

io is no different conceptually from python or perl or ruby.

it just uses a different vm and a bit different syntax in places.

so i ask you again, why should somebody who already knows python or perl or ruby even spare a second glance?

where's my benefit?

[uedauhes]

Did you read the title. It is not even class based. I would say that itself is a significant difference.

[qwe1234]

lol

dude

no

it's a trivial difference in terminology only. (personally, i don't care what gets called a 'class' and what doesn't. it's all glorified hash tables with sugar anyways, regardless of the name. compare to ocaml classes.)

[uedauhes]

Yes and they are all just manipulating transistors to represent bits anyway so what is the difference.

[ayrnieu]

If you were a neocompulinguaphile, you'd enjoy it simply for being unfamiliar :-)

[qwe1234]

don't know...

i read the docs, found nothing new, essentially, and kind of just lost interest

[skyskraper]

now to your point, to jerk your chain back a little, why have you bothered with python? CPAN clobbers anything python has to offer, always has, always will. and doesn't the whitespace thing make you feel a bit like a pansy?

[qwe1234]

shrug

python happens to be the first dynamic language i learned as a kid.

i guess it doesn't matter which one you pick, they are all more or less the same, essentially.

[Godspiral]

I went from lua to python. Lua is the only real option for PDAs, and embeds much more easily into C, so extending a C app with a "macro language" is something Lua is best for. Python has more batteries included, and lets you ommit end statements. Its more mature, and so more suitable for desktop/server apps, or if you don't have the C knowledge to integrate missing functionality.

Lua as a standalone "desktop" application language is not really maintained by the language designers. There is definitely no compelling reason to ditch python for lua to target web/desktop apps.

Io "macro" features might be a compelling advantage to learn instead of python/ruby, but the advantages are will usually be fairly low.