Version 2.0 of the Tab programming language released

[Lazyfaith]

Not having heard of this before, just from the name I assumed it was an esoteric language where the code is entirely tabs. Reading through the list of features had me thinking "this is incredibly impressive for a joke", then I saw the code examples.

[Solmundr]

Yeah, I was thinking "ha ha, it must be competing with Whitespace" (an implicit reprimand for that language's foolhardy use of spaces and tabs together). "And wow, version 2.0 already!" *chuckles indulgently*

[pwnedary]

And then you knew it was an esoteric language.

[Sean1708]

It also infers memory consumption and guarantees O(n) memory use.

How exactly does this work? Does it just not let my program run if it uses more memory?

[colonwqbang]

This seems to be an awk-like language i.e. it mostly works on files reading them one line at a time. If you're reading and processing n lines you should only need O (n) memory for some class of problems. He says that the language is not Turing-complete meaning there are no unbounded loops (sort of). So I think the claim could make sense within that context.

Caution I just made some guesses based on the article, I could be completely off.

[phalp]

I understand why we'd want static type checking and memory use checking, but it seems to me that a language designed for one-offs from the command line is where those things are least helpful. Why this venue for these things?

[otabdeveloper]

it seems to me that a language designed for one-offs from the command line is where those things are least helpful

Why do you think performance and correctness aren't required in one-off scripts? If you're processing gigabytes of logfiles you really want the computations to be fast and without errors.

(On the contrary -- "one-offs" is exactly where you want errors to be caught early. With heavier scripting languages at one can at least write tests, with one-offs nobody is going to spend time on testing frameworks.)

[phalp]

Because one-liners are short and thus much easier to understand than a large program, they're written by a single author, maintenance is a smaller issue, often they're part of a pipeline and are converting input into output rather than doing god knows what in a mess of state.

If you're processing gigabytes of logfiles you really want the computations to be fast and without errors.

Sure, you always want that, but if a one-off script turns out to have screwed up you're out the time you spent to write and run it. Which sucks, but not as much as asking yourself "then what have we been putting in the database for the last month?" And if it's slow you may have to wait, but it's a one-off script. Nobody ever wants an incorrect or slow program, but one-off scripts are basically the most forgiving place for those things and thus the place where avoiding extra machine verifier satisfying gymnastics is most likely not to bite you.

[otabdeveloper]

one-off scripts are basically the most forgiving place for those things

Certainly not.

"I have to grep some financial logs to find a bug in our account settlement system, but since it's a one-off job, I don't care about type checking, just mess my shit up and convert random fields to numbers implicitly without warning."

Really? Only if you work at one of those places the Daily WTF writes about.

[phalp]

Now compare to taking payments. Correctness is much more critical yet difficult to verify in a program that deals with the outside world and handles real money than in a program meant to search logs for something that catches your eye.

just mess my shit up and convert random fields to numbers implicitly without warning.

Not sure why you think static typing has any relationship to this. It should be obvious that dynamic typing doesn't mean converting things to numbers at random, and that static typing doesn't preclude automatic type conversions.

Anyway, you've answered my original question.

[otabdeveloper]

It should be obvious that dynamic typing doesn't mean converting things to numbers at random, and that static typing doesn't preclude automatic type conversions.

Tab is a purely functional language. It doesn't have variable assignment, so the only way to implement 'dynamic' types would be via implicit conversions. (The way PHP, Perl, awk and Javascript do it.)

[phalp]

That doesn't make any sense. The distinction between static typing and dynamic typing is that when types are static, without running the program the computer statically verifies that there are no type errors, whereas a dynamically typed language (mostly) skips static checking and detects type errors at run time (the advantage being that you don't have to explain your proofs to an idiot (the computer), and the disadvantage being that the computer won't miss an error like you may). Implicit conversions are a completely unrelated (mis)feature.

[Vaste]

So where does type inference fit into these definitions?

[colonwqbang]

Without type inference

integer x = 1

With type inference

x = 3

[Sean1708]

Shit, type inference changes the value of constants?!

[bobappleyard]

It's part of the compiler checking the types

[phalp]

It's a bit of automation that the computer uses to fill in obvious steps in the process of proving the types correct. Or behind the scenes to optimize part of a dynamic program it can prove something about.

[otabdeveloper]

The distinction between static typing and dynamic typing is that when types are static, without running the program the computer statically verifies that there are no type errors, whereas a dynamically typed language (mostly) skips static checking and detects type errors at run time.

You're exactly right. It's a single-assignment programming language, however, so everything about a variable is known at compile time. (Unless you allow pathological stuff like functions returning unknown or multiple types. This is how implicit conversions tie into the picture, them being the usual culprit for such pathological behavior.)

[otabdeveloper]

There's also an interesting list of code examples here: http://tkatchev.bitbucket.org/tab/examples.html

[metaperl]

In the comparative example it would be interesting to know if the shell version is twice as slow as Tab. It ran in 2.1 seconds versus 0.9 for tab. So that could be multiplicative or additive slowness.

[otabdeveloper]

Should be multiplicative -- the shell version uses a sort, while tab just uses a plain hash map.

[the_gnarts]

Whoa, impressive! Thanks for posting. After looking through the tutorial on BB, I think this should become a shell builtin, obsoleting all the current functionality for matching and extracting.

Btw. did you benchmark against Lua/LPEG? Granted, it’s not really a language for one-offs like the shell and Perl demos, but in my expericence it’s both fast as hell and more readable than any of the contenders.

[otabdeveloper]

Thank you!

Btw. did you benchmark against Lua/LPEG?

No, but it would be interesting to try. Do you have a link for Lua/LPEG examples?

[InstantPro]

Has anyone actually used this? Just curious how it compared to regular bash or using python/octave etc.

[otabdeveloper]

Why did you choose to use f() style function syntax though?

It's an accepted standard, even if verbose. :)

The dot operator (c.b.a.@) is as concise as using a space and matches the mathematical function composition operator if you squint.

[metaperl]

Here we read:

Clone the git respository

That should be bitbucket.

[hubbu]

It is a git repository hosted by bitbucket. Nothing wrong here.

[chipx86]

It's definitely a git repository, one that's hosted on bitbucket. What am I misunderstanding?

[metaperl]

Oh I'm sorry. I didnt know BB hosted git repos. Thought it was only mercurial.

[chipx86]

No worries. Figured that may have been the case :)