Little is a statically typed, C-like scripting language(little-lang.org) |
Little is a statically typed, C-like scripting language(little-lang.org) |
>We (BitKeeper folks) did our GUI interfaces in Tcl/Tk years ago because it meant we could have one gui person and get the same gui tools on Windows, Mac, Unix, and Linux.
>While some of us could switch from C to Tcl easily, our pointy-haired boss could not, he's mostly C and would lose about a half a day to get back into Tcl.
>Success was realized when one of our engineers, who is not a Little fan, fixed a bug in a patch that flew by in email without realizing it was Little instead of C
I'm surprised to see it getting some attention but happily so. Little is what I'd like C to evolve towards, there is a lot of useful (to me) stuff in the language.
I'll wander through the comments and reply where I can.
Jeff Hobbs from the tcl community helped as well. I have pictures of that group of people. Jeff helped a lot, he wanted this, I could say why but I don't want to speak for him.
Little is what I'd like C to be but those guys made it happen.
I'm amazed that Little got some traction, happy that it did for a moment, those guys deserve all the credit, I was a whiny dude wanted a more C like thing and they gave it to me.
On the other hand, we didn't make enough for everyone to retire if they wanted to. We had a github like offering and it's pretty clear that we should have put a bunch of money into that and open sourced BitKeeper.
All I can say is it is incredibly hard to make that choice when you have something that is paying the bills. I tried to get Sun to do it with the BSD based SunOS and they wouldn't. And even though I had that vision for Sun, when it was my livelihood, I couldn't see the path to doing so.
Shoulda, coulda, woulda, my biggest regret is not money, it is that Git is such an awful excuse for an SCM. It drives me nuts that the model is a tarball server. Even Linus has admitted to me that it's a crappy design. It does what he wants, but what he wants is not what the world should want.
It says a lot that we have a bk fast-export and we can incrementally run that and get idempotent results. As in go from BK to Git on an ongoing basis, have two people do it in parallel and they both get bit for bit identical results. If you try and go the other way, Git -> BK, if you do it in parallel you get different results because Git doesn't store enough information, so BK has to make up the missing bits.
Git has no file create|delete|rename history, it just guesses. That's my biggest regret, I wish Linus had copied that part.
It was good run, not many software companies get an 18 year run. I'm fine with it, would have liked to do more for my people.
Though, when we were shutting things down and I was bumming that I had not gotten retirement money for all of my people, one of them said something like "Dude, are you kidding me? My best friend barely knows his kids, he is out the door by 7am to fight Houston traffic and not home until close to 7pm. My commute is from my bedroom to my office down the hall. I've got to help my wife with the kids, I see the kids all day every day, my life is infinitely better than my friend's life and you gave that to me. You're fine."
I'm a wimp, I teared up a bit, that was the nicest thing he ever said to me. It's not just about money.
When we were still in business, each new SCM that came out, we'd hold our breath until we looked at it and said "No weave!"
For those who don't know, the SCCS weave is how your data is stored. Most people are used to something like RCS which is patch based. For the RCS trunk, the head is stored as plain text, the previous delta is a reverse patch against the head, lather, rinse, repeat. Branches are forward deltas, so if you want to get something on a branch, you start with the head, apply reverse deltas until you get to the branch point and then forward deltas until you get to the branch tip. Ask Dave Miller how much he loved working on a branch of gcc, spoiler, he hated it. With good reason.
SCCS has a weave that is not aware of branches at all, it only knows about deltas. So you can get 1.1 in exactly the same amount of time as it takes to get head, it is one read through all the data. bk annotate (git blame) is astonishingly fast.
And merges are by reference, no data is copied across a merge. Try that in a patch based system. How many of you have been burned because you merged in a branch full of code that someone else wrote, and on the trunk all the new data from the branch looks like you wrote it, so you get blamed when there is a bug in that code? That's because your brain dead system copied code from the branch to the trunk (Git does this as well, that's what the repack code is trying to "fix", it is deduping the copies).
Weaves are the schnizzle, any SCM system that doesn't use them today is so 1980.
2000.txt documents the first 2000 resyncs (think bk pull) of the kernel.
Avocet was what you got when you took all my perl code and handed it to the tools group and they rewrote it in C++ (which they later admitted was a horrible idea). The only thing of mine that they kept was smoosh.c and that was because not a single one of them had the chops to write that code (yeah, there was no love lost between me and the tools group).
BitKeeper is what Avocet could have been if Sun had not stopped me from doing any more work on NSElite (I was 1 guy who was coding circles around 8 tools people and they didn't like it). Shrug. C++ was just wrong, perl4 was just way faster to code in, and when I needed performance I coded in C. It's not my fault they picked the wrong way to go about things. (That, BTW, was the first time I ever personally saw that you really can have one guy who can do the work of 8, almost, but not quite a 10x programmer :-)
I think this is a super interesting project. It reminds me what Groovy is to Java, but backwards. Groovy is a “looser” version of Java that compiles Java. Little is a “stricter” version of TCL that compiles TCL.
One could release this "language" as a distribution of the inner language's compiler together with a wrapper (like C++ originally was to C), that, rather than adding features and compiling down, just analyzes the source file and errors out on use of forbidden syntax; or, if no forbidden syntax is used, just passes your code straight through to the inner compiler. A bit like a pre-commit-hook style checker, but a pre-compile-hook style checker.
Those commands effectively make any tcl function be able to operate as an f-expr (in old lisp parlance). Effectively (this is a simplification), an fexpr is a runtime macro, as opposed to the more traditional lispy compiletime macro.
Its what makes tcl feel more like a lisp-for-strings. Much of the truly horrible tcl code out there in the wild is from folks who try to use tcl as just another c-style scripting language.
Treat it more as a lisp, and it some of its inherent elegance shines through.
My $0.02 anyway ...
Compiles to Tcl byte codes
Perl has a lot of good ideas and things I find myself missing a lot when I use Python or JS (autovivification being probably #1) but IMO these one or two symbol magic variables would generally be improved if they were more descriptive, with maybe one exception for $_/@_.
Although I must admit reminiscing about this made me realize how much I miss Perl now that I'm forced to use Python for work.
Yet another horrible hack in Perl that for some reason is advocated for. Optional chaining / null propagation is a much, much better idea and shouldn’t have been any harder to implement.
My 3rd rewrite was very stylized and, I felt, maintainable. Which proved to be true as I had to fix bugs in it.
I did weird stuff like using $whatever as the index into the @whatever array.
But I digress. On the <>, Little has argv so you can do
int main(string argv[]) { int i; string buf; FILE f;
if (defined(argv[1]) && streq(argv[1], "-") && !defined(argv[2])) {
while (buf = <STDIN>) bputs(buf);
} else {
for (i = 1; defined(argv[i]); i++) {
if (defined(f = fopen(argv[i], "r")) {
while (buf = <f>) puts(buf);
fclose(f);
} else {
fprintf(stderr, "unable to open '%s'\n", argv[i]);
}
}
}
return (0);but why would you want to when all of that is
int main(string argv[]) { string buf;
while (buf = <>) puts(buf);
return (0);I mean, come on, that's cat(1) in 8 lines of code.
edit: I need to learn hacker markup. My code looks like crap.
http://mcvoy.com/lm/L/tcl/tests/langbench/
some results in the README. Perl holds up well. These are probably 10 years old though.
If you can make one language strongly typed, and one weakly typed, then you should be able to build one language which can do either/or, depending on a compiler flag. Then you simply decide before you start writing your code whether you want to write it weakly typed or strongly typed, and pass the correct compiler option.
Take that same idea, but add in every language's quirks, and just enable/disable them. Then we wouldn't need to constantly reinvent languages, because we'd have one that can do everything.
Otherwise we're going to keep re-writing the same damn thing for hundreds of years, and that just seems like such a pointless waste of effort.
https://thenewstack.io/larry-walls-quest-100-year-programmin...
set foo[i] = ""
In Little you can tell, we'll return undef (your clear "error" though in these languages it is a supported feature, not an error). So we support the auto expanding array but give you that extra bit of info that you are past the end.
Can someone explain what this does? Is this some Perl or Tcl thing? Unfortunately I've never used either :)
undef is both a function and a (non) value. It is the main reason Little never got pushed back into tcl, the tcl crowd hates the idea that there can be a value for a variable that is undefined. I found that very useful, for example, undef is the error return from any function. Just made sense to me, didn't make sense to the Tcl people.
Given the context, in little-lang, it appears to delete argv[1] and shift all of the right of that down, such that argv[2] becomes argv[1] and so on. That's so that the the "while (buf = <>)" construct used right below it doesn't process the regex as if it were a file to "grep" through.
In Perl, you would typically do it this way...
if (!defined(my $regex=shift(@ARGV))) {
die("usage: grep regexp [files]");
}I really wish more languages would adopt this syntactic sugar.
Personally, I would love a gcc --little dialect complete with a String type (and others) that is garbage collected and auto resized just like tcl/Little. With all the other Little goodness in there. Man, that would make C super pleasant. And it wouldn't be a new syntax like Go/Rust/whatever.
It had left me wondering what had caused it. There was a thread a few weeks ago where the old guard were describing an actual attempt to game the system, and I wondered if we were seeing a version of that being played out.
So Little looks a lot more like C than Pike does. And I like it that way. It's not for everyone but C programmers will probably like it.
Lisp people had bad ideas along the way. They recognized that this is the case and got rid of those ideas, in some cases documenting some of those choices.
Null propagation is nice too, but it doesn't address all the uses cases of autovivification when you have, say, a hash table of arrays and you want to insert a new entry in an array, creating it if it doesn't exist. In python you have to use setdefault which I always found clunky.
You can bind to a non-existing hash element (even multiple levels deep) and it won't exist until you actually assign to it:
my %h;
my $c := %h<a><b><c>;
say %h<a>:exists; # False
$c = 42;
say %h<a>:exists; # TrueThat man page isn't the most clear. upvar gives you a way to modify a variable in the calling context (and I think it can go up more than one stack frame).
It's a way to pass by reference rather than the default pass by value (how tcl passes is more complicated than that for performance but the default semantics are pass by value).
It's a facepalm-stupid thing to put into a programming language. Programs that use it will not be efficently compilable; the compiled code will have to provide upvar access similarly in order to make them work.
When compiling a function, you don't know which callee might ask for an upvar, so you can't optimize away variables or keep them in registers across calls.
int main(string argv[]) { string buf;
while (buf = <>) puts(buf);
return (0);
}Edit: sent an email to him, we'll see.
If you're already aware that ARGV exists, you'll guess that ARGF might be used in relation to it, and so when writing a CLI program that uses ARGV, you might wonder if ARGF could simplify your code and look up what it is/does.
These ultra terse shorthands make some sense in the shell because it's meant for interactive, write-only commands but a scripting language should be a little more verbose and consistent IMO.
while (buf = <>)
did. So I didn't want to invent a new syntax, there is way too much of that going on, I like C, I like perl, pull the useful stuff from each and move on.
I freely admit it's not how everyone would do it.
I think <> as a fancy readline and _ as a default/throwaway variable does really improve readability and lowers the mental load of understanding programs.
Some recent discussion of pijul on HN:
Perhaps I need to write up how weaves work in more detail. Once you get that, you won't want an SCM based on anything else.
I thought that was clever given that tcl's reference counter was signed and it only uses positive values. So we made it unsigned and got the bit for free.
So yeah, there is some sloppiness there. Tcl tends to use "" as sort of a null or undef so lots of stuff just works but no promises on that.
This is sloppy simply because the Tcl die hards (are there any left?) refused to see the value of undef, a value for a variable that said there is no value. We used it all over the place, there clearly is value. They didn't see that, Little never got pushed back into the Tcl source base so Tcl never thought about undef.
It is what it is, we live in an imperfect world. I tried.
Consider
char *p = 0;
some complicated code that should have set p but didn't...
char c = *p; // SEGV
So do you have a way to push that error all the way back to wherever you think it should be pushed?
The array access should error out on the line that it happens.
The dereference could print a line of the last assignment, but this isn't what was being talked about.
In Tcl, stuff just gets auto expanded on assignment and returns "" (I think) on dereference. We chose to return undef. I'm not sure what the problem is.
I can't be the only one who'd be interested in your views on the general developments for such important tools of our trade. Have you written about it anywhere? I'll pre-order "Larry walks us from SCCS to the git monoculture".
Unfortunately, even now, it seems that there is a lot catching up to BK still to be done. To be fair, we had kernel level programmers working on it, we don't think anyone will pick up our code, you pretty much have to be a top 1-2% programmer to work on it, it's all in very disciplined C, people don't seem to like that any more.
So far as I know, BK is the only system that gets files right, we have a graph per file, everyone else has a single graph per repository. The problem with that is the repository GCA may be miles away from the file GCA; BK gets that 100% right, other systems guess at the GCA. Graph per file means each file has a unique identifier, like an inode in the kernel. So create/delete/renames are actually recorded instead of being guessed at. SCM systems shouldn't guess in my opinion (actually in anyone with a clue's opinion, would you like it if your bank guessed about your balance? Of course not, so why is guessing OK in an SCM? It's not). Graph per file means that bk blame is instant no matter how much history you have.
BK is the only system that even attempts to get sub-modules (we call them components) right. Where by "right" I mean you can have a partially populated collection and you get identical semantics from the same commands whether it is a mono-repo or a collection of repos. Nobody else has anything close, Git sub-modules turn Gits workflow into CVS workflow (no sideways pulls).
I tried my best to show what we did in BK at that conference, I have no idea if they will swipe any of it. It's not like BK is perfect, it didn't do everything, no named branches, a clone is a branch, which is a model that absolutely will not scale to what people are doing today (we can argue whether TB repos should exist, but they do).
But for the problems BK did solve, it tended to solve them very well. Hell, just our regression tests are a treasure trove of things that can go wrong in the wild and we open sourced both the tests and the test harness.
Was the conference recorded? I've tried searching, but I'm not turning anything up.
As an outsider you get my worthless full agreement on strictness of history, and on solving the monorepo or vendoring dilemmas. My employer at the time of the upheaval was a bitmover customer, and as we slowly switched away one repo at a time it definitely felt like a sideways step. I'd hesitate to say backwards because it did come with some big process improvements for us, but definitely not forwards.
I'd surely have been proud of solving problems with the quality that BK did too. I remember playing with a lot of the open source systems of the time¹, and none of them were in the same league. I'll make no apologies for this sounding like truly weird fan mail.
¹ I'm remembering hg, darcs, monotone, $some_implementation_of_arch, prcs, codeville but there was a lot of people in the space to some degree.
Recent article on Pijul: https://initialcommit.com/blog/pijul-version-control-system/
Oh my oh my.
One of the oddest things I more recently learned about Git is that you can’t create empty folders. The workaround is to create an empty file (e.g., a README)!
That being said, entire careers are built on this powerful yet odd tool that has somehow become the most popular SCM system in the world.
The convention I've seen is `.keep` and `.gitkeep`.
I've experienced how Git's lack of file rename makes it hard to follow changes through directory and file reorganization. This made me reluctant to reorganize, as I learned the problem space. The general, long-term impact may be increased ossification pressure.
OTOH linus's content addressable system is absurdly, compellingly simple, and does 90%. It's disproportionately simple. A dilemma!
BTW I think many companies get killed that way. Refusing revenue to profit must be pollyanna - except for github. OTOH keeping customers is how great companies get killed, according to Christensen (the innovator's dilemma).
Been open source for years
I also explained a huge difference between the two already (you know how large an array is and can detect an out of bounds access when it happens).
We just thought it would be clever to return undef if you were out of bounds, which tcl code would see as "" which is what you'd get in tcl. But Little code could actually tell you are past the end.
In my mind, which many have argued isn't the best, it's a reasonable design.
You keep trying to push backwards to a design point where arrays are fixed in size at declaration and that is not how tcl (or Little) works.
You can see how this is getting confusing.
> So there is no error to catch.
Thing is, you're already catching the error because "Little code could actually tell you are past the end" and "return undef if you were out of bounds" - you're just smooshing the error under the carpet into an `undef` return rather than bombing out with an OOB error (which is what I think GP was actually after.)
(If Little returns `undef` for OOB and `""` for in-bounds-not-set, you can detect the OOB access error in your own code but that hasn't been made clear, I don't think?)
Apologize for saying BK is quality? None needed, we prided ourselves on producing a quality product. And great support, our average response time, 24x7, was 24 minutes. It was only that "slow" because we were North America based. If you only considered the US work week, response time was usually under 2 minutes, but that's not reasonable because we had customers all over the world.
I'm gonna start with a write up of the SCCS weave, with a goal that it is enough of a spec that you could go implement it. Maybe add some notes about how I did it because the way I did it was unusual and had the side benefit that you could extract the GCA, left tip, and right tip for a merge in one pass.
The thing that GP was asking for, an OOB error, is not a thing in a language where there are no bounds.
But I assembled a team of people better and smarter than me, I did my best to keep the code simple but I didn't always succeed.
If you, or anyone, wants to pick it up, I'm happy to answer questions.
At this point, the trick to creating a sizable git alternative I think is to Trojan horse coding into a new realm with “no-code” like apps.
One of my favorites is Fossil by Richard Hipp. I wonder what your thoughts on it are. I think it is RCS, but usability wise I think it’s way ahead of git.
I just recently learned C and I really like the coding style Hipp uses as well. :)
But no disrespect intended towards Richard, I've met him plenty of times and enjoyed it each time. Great guy.
Patch based systems are idiotic, that's RCS, that is decades old technology that we know sucks (I've had a cocktail, it's 5pm, so salt away).
Do you understand the difference between pass by reference and pass by value? You must, but in case you don't, you can pass by reference in sizeof(void *), 4-8 bytes. Pass by value and you are copying sizeof(whatever it is you are passing) onto the stack. Obviously, pass by reference is immensely faster.
But in SCM, it isn't just about speed (and space), it's about authorship. In a patch based systems, imagine that there is user A who is doing all the work on the trunk, there is user B who is doing all the work on a branch, and then there is user U who is merging the branch to the trunk. Lets say B added a bunch of work on the branch, it all automerged. U did the merge. In a patch based system, all of the B work is going to be copied (passed by value) to the trunk and the authorship of that work will change from B to U (since U did the merge).
Flip forward to a month from now, the code has paniced or asserted, whatever, B's code on the trunk took a crap. And people are running git blame to see who did that and who did it, U did. But U didn't, B did but U merged it and it was a copy so it looks like U did it.
That's just the SCM being dishonest because it has no choice, it is pass by value.
Weaves are pass by reference. If you merged in BitKeeper and it automerged, you run blame (we call it annotate but I should make blame be an alias if I haven't already, I'm the guy that came up with blame as that verb), you would only see A and B as the authors.
Weaves mean authorship is correct and that whole repack nonsense that Git does? Yeah, that goes away, you are passing every thing by reference so there is only one copy of the code no matter how many branches it has been merged from/to.
Anyone who is pushing a patch based system (and Git is one as well) just doesn't have a clue about how to do source management. Maybe something better than a weave will come along (and if it does, rbsmith will do it, that guy bug fixed my crappy weave implementation) but I think it will just be a better weave with new operators like MOVE (current weaves know INSERT and DELETE, that's it).
Sorry if I'm being a dick, not looking for sympathy but I've got health problems, my feet hurt like crazy and I get kind of terse at the end of the day. If you truly want to understand more, and this goes for all of hacker news, I'm happy to get on a zoom call and talk this stuff through. And it is blindingly obvious I need to write up the SCCS weave and I will do so, you guys have inspired this 58 year old, burned out, can't code to save his life, dude to at least try and pass on some knowledge. I would love to be working with some young person who has some juice and pass on what I know. I don't know everything about SCM but I know a lot. I'm done, it's time for someone else to carry things forward, I'll help if you want. The world deserves a better answer than what we have now.
I was about to reply point by point with arguments, but I changed my mind:
I don't think I'd be interested in that conversation, the comment above is worse than a public display of a very poor understanding of Git and Pijul: it also shows a complete ignorance of other actors in the market. It turns out the market leader for big repositories, Perforce, is itself based on RCS, possibly (but I don't know for sure, since Perforce is proprietary) because RCS scales much better to large binary assets than other solutions (I'd argue Pijul solves that, but that's beside my point).
I am a big fan of Git, Mercurial and Darcs myself, my co-author on Pijul was actually a maintainer of Darcs for many years, and I'm actively collaborating with the maintainers of Mercurial at the moment. And even though Perforce and Plastic are closed-source, they do solve one problem (scalability) which distributed systems are only beginning to understand (if there's one thing I think we've achieved with Pijul, it is about getting beyond the "distributed vs. scalable" trade-off).
Here's my take on the comment above: I don't think you can build good systems without understanding how others are made. There are no free lunches, no silver bullets, no geniuses. Only good ideas, bibliography, and hard work.
The comment that RCS scales for binaries couldn't be more wrong, RCS hates binaries with a passion.
The fact that you didn't address any of the points I raised says you either don't understand what a weave file format is, or, you do, you recognize it is a much better format but don't want to talk about that.
This part of this thread reminds of something Ron Minnich once said: "Don't worry about people stealing your ideas, you are going to have to cram them down their throats".
I'll drop it, we can revisit when I write up how weaves work. I don't think any objective person would argue that a patch based system is as good, let alone better.
> I've built two commercially successful systems,
This is a great achievements, congrats on that!
All I was saying in my previous comment was, these very cool achievements don't prevent you from calling all other people "idiotic", and from saying "they don't have a clue" without even looking at their designs, or even thinking that they might have had ideas different from yours.
Also, calling Git "patch-based" is quite wrong, but my point wasn't technical.
That isn't what I meant, I was actually talking about Perforce. RCS doesn't even handle multiple files.
I'm sorry if I pissed off the other guy, but I'm retired, and I'm tired, and I have no interest in arguing with people who don't get it. But it's on me to provide the info that lets them get it. I'll do that and what people do with it is up to them.