C for All

https://plg.uwaterloo.ca/~cforall/

by etrevino • 8 years ago

376 312 8 years ago

plg.uwaterloo.ca

Dinux2• 8 years ago

This has been tried many times before, and eventually all these attempts die a lonely death. Why use extensions anyway? If one desired the luxury of modern scripting languages, switch to C++, Rust, Go or one of the other alternatives the article mentions.

pjmlp29• 8 years ago

Because regardless how some of us might dislike C and its security related issues, the truth is that no one is ever going to rewrite UNIX systems in other language, nor the embedded systems where even C++ has issues gaining market share.

So if one finally manages to get a safer C variant that finally wins the hearts of UNIX kernels and embedded devs, it is a win for all, even those that don't care about C on their daily work.

Until it happens, that lower layer all IoT devices and cloud machines will be kept in C, and not all of them will be getting security updates.

Dinux2• 8 years ago

I do not question the usefulness of C, I use it in my daily work. What I am saying is that most C developers that use the language day-in-day-out know quite well what they are doing, and don't need yet another non-standard way of writing the code. Safety is a good point, but the initiative doesn't even mention the word, and there is no reason to assume the C-for-All extension targets safety at all

kerkeslager3• 8 years ago

What makes you think that a safer C variant would win the hearts of UNIX kernels and embedded devs any more than C++ (which started as just a C variant).

zombieprocesses• 8 years ago

So if one finally manages to get a safer C variant that finally wins the hearts of UNIX kernels and embedded devs

A safer variant wouldn't be C. What makes C great for OS development is that it is just a step above assembly and you as a developer are given tremendous amount of power to do good and evil. C#/Java are programming languages with training wheels and it's great for application development. But for low level coding required for OS, network stacks, databases, etc, you really have to take the training wheels off.

I suppose you can try and make the C type system more stringent, but then it wouldn't be C. And considering they are aiming for backwards compatibility with existing C and its immense code infrastructure, they will have to keep the "flaws" in c for all.

Time would be better spent making the libraries/kernel/etc sturdier but if they can pull it off and win the hearts and minds of OS developers, then so be it.

Also, people have been trying to sideline C for decades. Each attempt has only reinforced C's standing and reminded us why C is so essential for OS development. Anyone remember the ill-fated attempt by Sun with their JVM centered JavaOS?

dralley• 8 years ago

counterexample: RedoxOS

Although it's more along the lines of Plan9 - a unix-like system that ignores the bits of POSIX that really suck.

zzzcpan4• 8 years ago

Which means that minimal requirements to win kernel and embedded devs is to integrate well with the rest of the C ecosystem, including myriad of C compilers and to be really well suited for low level work. This excludes pretty much all ideas, but meta languages that produce C code. Might even be necessary to promote the language itself not as a new language, but as a meta preprocessor for C to avoid alienating developers. But realistically this is not feasible nor necessary. There are much more feasible ideas to improve safety, than forcing half of the world to learn a lot of new things and change.

pjc502• 8 years ago

The trouble with a "safer C variant" is that it must remove features, or at least more heavily constrain programs to a safer subset of the language. This makes it not backwards-compatible.

I think the only successful "subset of C" is MISRA.

s73v3r_4• 8 years ago

They're not going to rewrite any of them in this dialect, either.

snarfy2• 8 years ago

You can use c++14 on embedded devices just fine, and people do.

michaelcampbell• 8 years ago

Because regardless how some of us might dislike C and its security related issues, the truth is that no one is ever going to rewrite UNIX systems in other language

Now will they in this.

thanatos_dem• 8 years ago

Site is down... that doesn’t exactly bode well for an article seemingly about programming.

mbel• 8 years ago

For convenience of other readers, here is a version cached by Google: https://webcache.googleusercontent.com/search?q=cache:wEWECJ...

wolfgke2• 8 years ago

Or here by archive.org: https://web.archive.org/web/20180323124625/https://plg.uwate...

CO-VAX• 8 years ago

"Powered by Huawei" -- ironic, isn't it?

BruceIV17• 8 years ago

[actually on the Cforall team] Huawei has funded the project for the past couple years, the web server is just our university research group's web host, which we didn't expect to get this much traffic on (it wasn't one of us who put this page on HN). We've been running fairly low-profile for the moment, but should make a beta release later this summer.

chimmy_chonga• 8 years ago

to be fair, a lot of smaller sites go down after being posted on hackernews due to the huge uptick in traffic.

castratikron• 8 years ago

GNU C is probably my favorite extension of C. There's a lot of good stuff in there. The vector extensions make it really easy to write platform agnostic SIMD code.

https://gcc.gnu.org/onlinedocs/gcc/C-Extensions.html

blattimwind• 8 years ago

I've used nested functions more often than I'd like to admit, because dealing with insane callback-heavy APIs is made a lot easier with them.

s73v3r_4• 8 years ago

I've never really thought to use nested functions for that. I guess I've never really thought of what nested functions were for.

Gibbon13• 8 years ago

I love using nested functions when I have to write state machine code. It's a hella a lot better than the old school way using macros to do the same thing.

kerkeslager3• 8 years ago

Also, the compare-and-set operations enabling lock-free code is pretty cool.

Sir_Cmpwn• 8 years ago

Please don't use GNU C, or any other non-standardized version of C. A huge part of the reason C that is so widespread is because it's a well defined standard implemented by many compilers for many platforms. GNU C is defined by its implementation, which is awful.

emilfihlman6• 8 years ago

There is nothing wrong with using GCC extensions.

Also, porting C is not that hard and does not require you to touch internals that much.

jcelerier9• 8 years ago

Please don't use GNU C, or any other non-standardized version of C.

Everything standard was once non-standard ; if no one uses it it will never be standardised and we will be left with a poor status quo. For instance, there wouldn't be int8_t, etc... if people weren't using non-standard macros beforehand. Likewise for atomics, threads, etc.

exDM69• 8 years ago

I disagree with this. A lot of GNU C works on both, GCC and Clang which covers most platforms out there.

Those extensions are useful and allow better portability across architectures. E.g. SIMD extensions is much better than writing two implementations with NEON and SSE intrinsics.

pcwalton2• 8 years ago

Please do use GNU C if you're going to use C. The viral nature of the Linux kernel has forced GNU C to be an important de facto standard. Take advantage of that!

alerighi2• 8 years ago

Why not ? If I don't care about portability because for example I'm writing a software that it's meant to be used only on Linux because it uses Linux specific libraries or system calls and I know that there gcc it's the standard I use the extension if they can simplify my code ?

LaneRendell• 8 years ago

Hallelujah.

hsivonen• 8 years ago

Considering how hard it is to write truly exception-safe C++ and considering how major C++ code bases don't allow exceptions, adding exceptions to C does not seem like a good idea.

codemac• 8 years ago

I've always liked the idea of djb's boringcc[0], except with different definitions of undefined based on what users were using C currently with. This would allow people to "upgrade" into boringcc with their current code bases. So with a single invocation of a compiler, you couldn't use more than one set of defined undefined behaviors.

[0] https://groups.google.com/forum/m/#!msg/boring-crypto/48qa1k...

platinumrad3• 8 years ago

I would love a gcc optimization level, like -Og which only applies optimizations that don't interfere with debugging information, where all undefined behavior is specified.

Does anyone know if undefined behavior is specified in CompCert? Or does CompCert simply not allow you to write programs with undefined behavior?

golergka4• 8 years ago

Whether exceptions are good or bad depends on what error handling strategy your product needs. For some software, it's better to try and recover no matter what. For others, complete failure is preferrable to operating with invalid state. Exceptions can be a blessing or a curse depending on what you need. Having them in your toolbox is certainly an advantage over having no choice.

xamuel2• 8 years ago

Having them in your toolbox is certainly an advantage over having no choice

I disagree. Dependencies, or coworkers, will use them despite your decision not to use them. When a dependency does use them, chances are the documentation is poor or non-existent.

"Recover no matter what" doesn't require exceptions. A common C idiom is to call a function like f(input, *err), where err points to memory where f can write error diagnostic info. Clunky, but I like how it makes the "exceptions" somewhat self-documented in the function signature.

jcelerier9• 8 years ago

Considering how hard it is to write truly exception-safe C++

Is "writing truly exception-safe" something that necessary ? for me, the biggest benefit of exceptions is that I can have some code throw from anywhere and display a nice error pop-up message to my user which informs me of what went wrong and revert what was currently happening during the processing of the current event, since the "top-level" event loop is wrapped in a try-catch block. Often enough, the user can then just resume doing whatever he was working on.

humanrebar2• 8 years ago

Is "writing truly exception-safe" something that necessary?

If you want your connections cleanly terminated, your temporary files removed, and your database transactions invalidated, yes.

pjc502• 8 years ago

If your code isn't exception-safe, then carrying on after an exception may crash the program.

antirez3• 8 years ago

So the mailing list and the other stuff are "internal only"? How is possible for external individuals to take part?

BruceIV17• 8 years ago

I'm actually on the Cforall team -- we've been running fairly low-profile for the moment (it wasn't one of us that posted the homepage to HN), but plan on making a beta release of the compiler and stdlib sometime this summer.

If you're interested in working on the project though, more hands are always welcome; I'd suggest contacting our team lead, Peter Buhr, his email is pabuhr AT the university domain Cforall is hosted on.

antirez3• 8 years ago

Thank you, I'm not able to provide a lot of help but I would like to follow the discussion, perhaps the sensible thing to do at this point is to wait for the first beta, then probably the mailing list will be open to everybody. Thank you for replying.

kodablah3• 8 years ago

Out of curiosity, why not do the development in public? Or is there a repo I missed?

emilfihlman6• 8 years ago

If there's one thing I would do to C it is to replace the normal datatypes with u8, u16, u32, u64 (ad infinitum) and their signed brethren s8, s16, s32, s64, ...

And don't start with the stupid (u)intXX_t.

kurtisc2• 8 years ago

You could just use macros or typedefs for the the (u)intXX_t types.

breadbox• 8 years ago

And therein lies the issue. Everyone does just that, causing needless clashes. If you're writing a library, you can either switch back to the standard type names in your external header file, or you include the typedefs/macros there as well. The former choice ruins some of the point of having these types, and might even mask cross-platform issues. The latter runs the risk of clashing with the user's owns typedefs, or with another library writer's typedefs. (And god help you if exactly one library writer chose to do it via macros.)

Nursie• 8 years ago

They aren't stupid, and they are both standard and available on nearly every system going. People absolutely should use stdint. h

I wish more would.

Ace17• 8 years ago

People absolutely should use stdint.h

Definitely. However, you have to admit the names (uint32_t) could be made less verbose, like "u32".

emilfihlman6• 8 years ago

You are missing the point. The question was about if I could change something in C.

I use stdint.h (and inttypes.h since fuck printf without it amirite) but u8 ... are just better.

bdamm2• 8 years ago

uint8_t is really not very hard to type.

Personally I would much prefer uint16_t over u16. Confusion over type handling is a source of some of the worst bugs. Remember, uint16 isn't the same as 16 bits if you consider endian-ness.

andrewmcwatters3• 8 years ago

I think C developers are harder to convince than developers who more regularly consume modern languages. I see no reason to use this over ANSI C.

kurtisc2• 8 years ago

C especially is used by EEs who are less likely to care for newer features.

platinumrad3• 8 years ago

EEs are why C89/C90 will be with us forever.

naasking3• 8 years ago

Looks pretty ambitious. My take from skimming:

* switch, if, choose and case extensions look good.

* I can see the justification for labelled break/continue, but looks pretty hairy. Might discourage rethinking and refactoring to something simpler.

* I'm wary of exceptions.

* I don't like the 'with' clauses.

* Weird to add syntax just for mutexes, but they integrate concurrency/coroutines later, so maybe it make sense.

* Tuples are generally useful, but C11's unnamed structs are generally good enough, ie. instead of [int, char] you can return "struct { int x0; char x1 }" or something.

* New declaration syntax is welcome, but the old syntax probably isn't going away, so I'm not sure it's a good idea.

* Constructors/destructors are good. Syntax looks weird though.

* Overloading is very welcome.

* Not sure about operators, but they have their uses.

* Polymorphism is welcome, though it looks a bit cumbersome, and it should come with a monomorphisation guarantee for C.

* Traits seem like too much for a C-like language. I can see the uses, and the compiler can optimize this well, but they're probably too powerful.

* Coroutines are cool.

* Streams look interesting, but the overloading of | will probably be confusing.

DSMan1952762• 8 years ago

I'm more or less in agreement, but I just though it was worth adding that the tuple's could actually have a lot of merit, I think I'd like to see them (Though I'm not sure the syntax is perfect parsing wise. It might be smart to prefix them, like `tuple [int, char]` or something.).

It seems like anonymous struct's fill the void, but a big problem with anonymous struct's is their types are never equal to any other, even if all the members are the exact same. So that means that if you declare the function as returning `struct { int x0; char x1; }` directly, it's actually mostly unusable because it's impossible to actually declare a variable with the same type as the return type. Obviously, the fix is to forward declare the `struct` ahead of time in a header file somewhere and then just use that type name, but that gets annoying really fast when you end-up with a lot of them. The tuples would allow you to achieve the same thing, but with a less verbose syntax and would allow them to be considered the same type even without forward declaring them.

naasking3• 8 years ago

So that means that if you declare the function as returning `struct { int x0; char x1; }` directly, it's actually mostly unusable because it's impossible to actually declare a variable with the same type as the return type.

Are you sure about that? I remember playing with this last year and structural equality seemed to work when returning structures from functions. I was using clang, so it could conceivably have been an extension... (edit: some online C compilers do indeed return an error in this case)

If that's the case, then just make anonymous structs employ structural type equality and you have better tuples.

dimman• 8 years ago

"Without continued development of the language, C will be unable to cope with the needs of modern programming problems and programmers; as a result, it will fade into disuse. Considering the large body of existing C code and programmers, there is significant impetus to ensure C is transformed into a modern programming language."

Really? Lots of C code written today is written using C89/C90 or C99 std. I think if it's something that history tought us it is that C does _not_ need to be transformed into something else or we would already be happily using this "something else" today.

js83• 8 years ago

Not bad, but not much to call home about either.

Personally, I would like to see better support for immutability/purity and more first-class functions (does C still insists on functions to be global in scope?).

Also, I think user-defined constructors/destructors are a bad idea. I generally found that any side effects that are done in constructors and destructors are a nasty source of bugs. It's almost always better to use a factory method (function), which makes user-defined constructor/destructor useless as a concept.

jcelerier9• 8 years ago

It's almost always better to use a factory method (function), which makes user-defined constructor/destructor useless as a concept.

well, no. In languages with constructors, you can enforce invariants in your class and ensure that no object that does not respect the invariants exists in your system. If you only have factory methods, you can still construct objects "normally" then nothing prevents anyone from creating another object which does not respect them. Or you can hide your struct definition in an implementation file, but then you loose the ability to construct on the stack and have to dynamically allocate, which kills performance.

js83• 8 years ago

In languages with constructors, you can enforce invariants in your class and ensure that no object that does not respect the invariants exists in your system

Actually, it's not enough. If you can mutate the class variables (attributes), then you can always create a class that doesn't have these invariants enforced. The only way that could completely prevent invariants in the class being disrespected would be to have a strong, possibly dependent, type system.

For example, consider a function (method) that takes two objects of the same class and creates another object of the same class based on the two. During the construction of the returned object, invariants can be broken, and if this function contains an error, it will return an invalid object.

This is especially problematic with the RAII pattern. Because resource acquisition can fail, you have to allow for "broken" objects to be returned, which represent the resource not being acquired. In functional programming, this is done with sum types (and in general way with Maybe, for instance).

I would say I am against RAII pattern, because it gives people a false sense of security, as you have to deal with the resource not being acquired anyway (either by returning object in incorrect state or by exception). But if you forfeit RAII, you might as well get rid of user constructors and use factory methods (and simple data constructors and sum types) everywhere for simplicity and consistency.

enriquto3• 8 years ago

I'm all for the evolution of C, but this list...

1) has some downright idiotic things (exceptions, operator overloading)

2) has a few reasonable, but mostly inconsequential things (declaration inside if, case ranges)

3) is missing a few real improvements (closures, although it is not clear whether the "nested routines" can be returned)

bdamm2• 8 years ago

Agree 100%. Improvements to C would be things like removing "undefined behavior", not adding more syntax sugar. If anything, C's grammar is already too bloated. (I'm looking at you, function pointer type declarations inside anonymized unions inside parameter definition lists.)

bhasi• 8 years ago

function pointer type declarations inside anonymized unions inside parameter definition lists

Could you please provide a code snippet of this kind? Hard for me to visualize otherwise. Thanks.

geezerjay3• 8 years ago

Improvements to C would be things like removing "undefined behavior"

This nonsense again. I don't get this "undefined behavior" cliche. It seems it became fashionable for some people to parrot it like a mantra as a form of signaling. Undefined behavior just refers to something that is not covered by the international standard, and therefore doesn't exist nor should be used, but an implementation may offer implementation-specific behavior.

pmarreck• 8 years ago

Can you explain why exceptions and operator overloading are "idiotic" things? Are you from the Go school of boilerplate-error-checking-code design, or something?

adrift• 8 years ago

Sum types are the new trend.

dmitrygr2• 8 years ago

exceptions because in embedded contexts they may not always be a good idea (and C targets such contexts). overloading because it is too easy to abuse and as such it gets abused a lot by those who do not know better. The rest of us are then stuck decoding what the hell "operator +" means when applied to a "serial port driver" object

UncleMeat3• 8 years ago

Exceptions work great in garbage collected languages. Reasoning about exceptional control flow w.r.t. manual memory management is a total nightmare.

dmitrygr2• 8 years ago

Couldn't agree more. and i'll add another:

the suggested syntax is ridiculous. What is this punctuation soup?

   void ?{}( S & s, int asize ) with( s ) { // constructor operator
   void ^?{}( S & s ) with( s ) {          // destructor operator
   ^x{};  ^y{};                              // explicit calls to de-initialize

reza_n• 8 years ago

Constructs like closures come at a cost. Function call abstraction and locality means hardware cannot easily prefetch, instruction cache misses, data cache misses, memory copying, basically, a lot of the slowness you see in dynamic languages. The point of C is to map as close to hardware as possible, so unless these constructs are free, better off without them and sticking to what CPUs can actually run at full speed.

zzzcpan4• 8 years ago

Closures are logical abstractions and cost nothing, since they are logical. Naive runtime implementations of closures can of course be a bit slower than native functions, but so can be everything.

lloeki• 8 years ago

3) is missing a few real improvements (closures, although it is not clear whether the "nested routines" can be returned)

Ah, I wish Blocks[0] would have made to into the C language as a standard†... Although you can use them with clang already:

    $ clang -fblocks blocks-test.c # Mac OS X
    $ clang -fblocks blocks-test.c -lBlocksRuntime # Linux

Since closures are poor man's object, I had some fun with them to fake object-orientedness[1].

† or at least that the copyright dispute between Apple and the FSF for integration into GCC would have been resolved (copyright transferred to the FSF being required in spite of a compatible license).

[0] https://en.wikipedia.org/wiki/Blocks_%28C_language_extension...

[1] https://github.com/lloeki/cblocks-clobj/blob/master/main.c#L...

Someone• 8 years ago

From https://plg.uwaterloo.ca/~cforall/features:

    Exponentiation Operator

    New binary exponentiation operator '\' (backslash)
    for integral and floating-point types.

    2 \ 8u; // integral result (shifting), 256
   -4 \ 3u; // integral result (multiplication), -64

I hope that’s a documentation error. Otherwise, it seems designed for the “Obfuscated C for all” contest:

   int i = f();
   int j = i \ 3u;

Does what ‘\’ does really depend on the sign of i?

Sean1708• 8 years ago

The "shifting" vs "multiplication" is just an optimisation since

  x * 2 == x << 1

for any positive x. As far as I'm aware shifting a negative number is undefined, which will be why they use multiplication for negatives.

snarfy2• 8 years ago

C is an evolving ISO standard.[1] We are currently at C11.

The purpose of the project is to engineer modern language features into C in an evolutionary rather than revolutionary way.

It's also the purpose of the standards body. Why not propose these changes to the standard?

[1] https://www.iso.org/standard/57853.html

pjmlp29• 8 years ago

Maybe because one needs to buy a seat at the table, by making a formal proposal, pay the travel expenses on their own and get to win the hearts of others members when voting comes to be.

jessaustin3• 8 years ago

There is still time, right? Lots of standards update efforts have moved in and out of ISO and IETF.

sagichmal• 8 years ago

    Exception Handling

Oh no :(

rotrux• 8 years ago

looks like the University of Waterloo isn't on the cloud!

Anyone else having trouble accessing the site?

jessaustin3• 8 years ago

Without continued development of the language, C will be unable to cope with the needs of modern programming problems and programmers; as a result, it will fade into disuse.

C11 is pretty nice! C99 is too. One might think that "almost once a decade" is kind of slow for updates, but M$ have enough trouble keeping up with the current schedule. Of course TFA describes a possible direction for C2x, but they could have a more charitable attitude...

nine_k2• 8 years ago

will fade into disuse.

That's one thing I'd like C to do. It was an adequate language in 1970, but in 2018, we have a few better approaches that have a chance to turn into viable alternatives to C.

Of course, I don't see C falling into disuse any time soon. The amount of critical code written in C is enormous, without a way in sight to reasonably replace. So keeping C in a good shape is important, whatever shortcomings the language may have.

pjmlp29• 8 years ago

Not even that much in 1970, if you look into old papers about the systems programming languages being used at other research institutes besides AT&T.

pjmlp29• 8 years ago

Microsoft does not have any trouble keeping up with C, C++ and .NET Native are the future of systems programming on Windows.

C compatibility is kept to the extent of ANSI C++ requirements.

ANSI C++14 requires C99 library compatibility and ANSI C++17 was updated for C11 library compatibility.

http://open-std.org/JTC1/SC22/WG21/docs/papers/2016/p0063r2....

jessaustin3• 8 years ago

They are improving! Six years is less than fifteen.

insulanus• 8 years ago

Herb Sutter doesn't like C. That may be the reason that the compiler group at Microsoft don't put any effort into updating the C compiler to support newer features.

They do put a great deal of work into the C++ compiler, and seem to be doing a way, way, better job than they were in the late 90s.

That may be the other reason they don't update the C compiler with new features.

mar77i• 8 years ago

What's with the weird cryptic, trigraphish syntax for something common as constructors and destructors?

How are _init(struct obj o) _cleanup(sturct o) not enough? Okay, except those rare cases when you need a _new(struct obj o).

BruceIV17• 8 years ago

[on the Cforall team] It broadly matches our other operator-overloading syntax, where the ?'s show where the arguments go, e.g. ?+? for binary addition, ?++ for postincrement and ++? for preincrement. For something as common as constructors and destructors, a concise syntax is a desirable feature.

andrewmcwatters3• 8 years ago

What I get out of this is that you like to play with languages rather than make actual things with them.

adrianmonk• 8 years ago

Wow, they really hate object-oriented programming.

It's the one thing they immediately emphasize that their language isn't, and it's the one example they give for "disadvantages of multiple legacy design-choices".

flohofwoe• 8 years ago

IMHO there are better proposals for a "better C" language which fix some of the shortcomings of original C:

- http://c2lang.org/site/

- https://ziglang.org/

- https://nim-lang.org/

As long as the language is small and has good tooling, and (most importantly) can easily interoperate with C libraries (have a look at Nim for an really awesome C integration), it doesn't matter whether it is backward compatible with C.

C itself should stay what it is. A low level and simple language without surprises which is only very slowly and carefully extended. Languages that are developed "by committee" and add lots of new features quickly are usually also quickly ruined.

astrodust• 8 years ago

The biggest problem with C is not the language but the fact that the C standard library is so anemic. Where's the "Boost" for C?

earenndil4• 8 years ago

I've written in the past about C2[1]. Nim is aimed at bit of a higher level than a "c replacement" should. I don't really know much about zig, but from what I do know, I like it.

1: https://www.reddit.com/r/programming/comments/7ugm8e/c2_c_wi...

karlding• 8 years ago

Peter Buhr also teaches CS 343: Concurrent and Parallel Programming [0] at the University of Waterloo in a dialect of C++ that he has been working on [1], called uC++ [2].

[0] https://www.student.cs.uwaterloo.ca/~cs343/

[1] https://github.com/pabuhr/uCPP

[2] https://en.wikipedia.org/wiki/%CE%9CC%2B%2B

BruceIV17• 8 years ago

[on the Cforall team] One of our Master's students has incorporated the majority of the uC++ features into Cforall as well, with some neat extensions for multi-monitor locking in a way that doesn't introduce synchronization deadlocks not present in user code.

filereaper3• 8 years ago

As an alumni, I firmly believe there's room for a 4th year course in-addition to CS343. There's quite a lot in advanced control flow which can be covered.

I've always found it unfortunate that the university has courses from first year all the way to fourth year in Data Structures and Algorithms (all the way up to CS466/CS666) but Control Flow is treated like a secondary citizen.

andrewmcwatters3• 8 years ago

What a waste of tuition money.

TwoBit• 8 years ago

We already have this. Just use C++ and stay away from the features you don't want. If you want to enforce specific restrictions then start an effort to provide a formal C++ feature restriction specification.

chubasco• 8 years ago

I think I would prefer the Indiana Jones approach. "Leave it alone! It belongs in a museum!"

jokoon• 8 years ago

You would be right if OS kernels were not written in C.

Linux is pretty much deployed on a lot of hardware, it is still maintained, and it uses C.

Granted it is not the best language, but it's simple enough to do kernel development.

The same goes for cobol, it's the best paying language out there.

filereaper3• 8 years ago

uWaterloo uses an in-house language to teach advanced control flow, in my days it was uC++ built by Peter Buhr in CS343. They might have opted to use C for All now.

I've found it quite easy to spin up parallel tasks in uC++ if I needed both C++ and easy-to-use parallelism, the language isn't formally supported but for small student projects its pretty kick ass, also the prof who built it is just quick email away.

So all I'm all in favour of C for All as an alumni, hopefully it enriches the existing curriculum.

BruceIV17• 8 years ago

[on the Cforall team -- also a CS 343 TA] We've incorporated the main uC++ feature set into Cforall, but are still using uC++ for 343; maybe in another couple years when Cforall is stabilized a bit we'll give it to the students.

ndh2• 8 years ago

From https://plg.uwaterloo.ca/~pabuhr/:

The ability to write generic reusable programs, called polymorphism, is fundamental to advanced software engineering. I am interested in static type-systems providing polymorphism without the use of subtyping. The problem with subtyping is that it imposes significant restrictions on reuse when static type-checking is required. This work has resulted in a new dialect of C language, called Cforall, which adds parametric polymorphism and extensive overloading to provide a more general type-system.

rwmj• 8 years ago

Did they bother to ask any C developers what the pain points are? The kernel, qemu, libvirt, coreutils and gnulib developers really use C and POSIX to breaking point, and have some real problems that might be addressed in the language, but I don't see much evidence of those problems being addressed here.

Did they study existing code bases and bugs to find out how applicable these changes are to fixing real problems?

vanderZwan3• 8 years ago

It's a research language:

https://plg.uwaterloo.ca/~cforall/people

You can check the various Master Theses at the bottom of the page.

SidiousL• 8 years ago

I see they are adding an analog of the C++ iostreams, but I don't see a discussion of how to disambiguate between `sin' as in stream-in and `sin' as in the mathematical function.

Really, they should introduce some kind of modules or namespaces. Of course, C++ already has namespaces and will have modules sooner or later...

zestyping• 8 years ago

There are a lot of features thrown into this language that don't seem worth the learning costs they incur. What are the problems you're really trying to fix? Focus on the things that are really important and impactful, and solve them; don't waste time on quirky features that just make the syntax more alien to C programmers.

* `if` / `case` / `choose` improvements look fine, though not that important.

* Exception handling semantics aren't defined.

* `with` is pointless and adds gratuitous complexity to the language.

* `fallthrough` / `fallthru` / `break` / `continue` are all just aliases for `goto`. It's not obvious to me that we really need them.

* Returnable tuples look very nice.

* Alternative declaration syntax looks like a nightmare. If we were redesigning C from the ground up, a different declaration syntax might be better, but mixing two syntaxes is a terrible, terrible idea.

* References. Why? They only add confusion.

* Can't make head or tail of what `zero_t` and `one_t` are about, or why they would be useful.

* Units (call with backquote): gratuitous syntax, unnecessary and confusing.

* Exponentiation operator: gratuitous and unnecessary.

SolarNet• 8 years ago

Can't make head or tail of what `zero_t` and `one_t` are about, or why they would be useful.

I suspect it's the same problem C++ has/had (C++11 fixed it) with bools (see the safe bool idiom [0]). Basically treating a type like an integer (arithmetic object) and boolean (logical object) at the same time is problematic (especially for a "system" type meant for extending implicit system behavior). Because then I can do `if(BoolObject < 70)` when I only meant for `if(BoolObject)` to work (where "BoolObject" is some object evaluating to a bool, and by evaluating I mean coercing/casting).

Here it looks like they approached it by making 0/1 (effectively C's false/true) different types and relying on their simpler/more-powerful type system (e.g. because they don't have to worry about C++'s insane object system). Not a terrible idea if they were otherwise actually sticking to their goal of "evolving" C (most of their features are radical departures from the language like exceptions). C++11 solved it by clarifying how implicit explicit casting [sic] of rvalues works in certain keywords (which I strongly doubt anyone can say was the simpler way of solving the problem).

[0] https://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Safe_bool

kragen2• 8 years ago

Yeah, Ping, I agree. It reads like they missed the key lesson of C — in Dennis Ritchie's words, "A language that doesn't have everything is actually easier to program in than some that do." And some of the things they've added vitiate some of C's key advantages — exceptions complicate the control flow, constructors and destructors introduce the execution of hidden code (which can fail), and even static overloading makes it easy to make errors about what operations will be invoked by expressions like "x + y".

An interesting exercise might be to figure out how to do the Golang feature set, or some useful subset of it, in a C-compatible or mostly-C-compatible syntax.

I do like the returnable tuples, though, and the parametric polymorphism is pretty nice.

emilfihlman6• 8 years ago

Exponentiation operator gratuitous and unnecessary?

WHAT?

kragen2• 8 years ago

It doesn't improve readability. Compare:

   discrim = b² - 4ac;                  // Standard notation
   float discrim = pow(b, 2) - 4*a*c;   // C
   float discrim = b \ 2 - 4*a*c;       // C∀

I would argue that these are presented here in descending order of readability.

Also its typing rules are really complicated; apply it to two integers and magically you are thrown into the floating-point world where you can never be completely certain of anything, but if you use an unsigned exponent then you stay safely in integer-land.

dzdt2• 8 years ago

I bike-shedded in this thread about exponentiation. But taking a step back the bigger issue is there are so many poorly justified features thrown in.

I don't have the feeling that the authors appreciate the appeal of C as a simple language that maps closely to hardware features.

This is a big random collections of extensions that piqued some implementor's fancy. There is seemingly no effort at narrowing down to the cleanest or most important ideas. It totally kills the clean, simple aesthetics of the the base C languge.

vanderZwan3• 8 years ago

It looks like most people here are so eager to jump on the "this feature is good, this sucks, overal I'm not impressed"-bandwagon (with the typically unwarranted strong opinions that programmers always have when it comes to this) that they didn't bother to explore the rest of the website in more detail. Go to "people" page and you see that it's a language implemented by professors, PhDs and master students from the Programming Language group at Waterloo[0][1]. Scroll down and you'll see that a number of these features came from the master thesis of a student:

    Alumni
    Ph.D.
    
    Glen Ditchfield, 1992
        Thesis title: Contextual Polymorphism
    
    Masters
    
    Thierry Delisle, 2018.
        Thesis title: Concurrency in C∀.
    Rob Schluntz, 2017.
        Thesis title: Resource Management and Tuples in C∀.
    Rodolfo Gabriel Esteves, 2004.
        Thesis title: Cforall, a Study in Evolutionary Design in Programming Languages.
    Richard Bilson, 2003
        Thesis title: Implementing Overloading and Polymorphism in Cforall
    David W. Till, 1989
        Thesis title: Tuples In Imperative Programming Languages.
    
    USRA
    
    Andrew Beach, Spring 2017.
        Line numbering, Exception handling, Virtuals

So basically, it's a research language, more-or-less developed one student at a time.

[0] https://plg.uwaterloo.ca/~cforall/people

[1] https://plg.uwaterloo.ca/

edflsafoiewq• 8 years ago

Everyone wants to cripple switch by turning it into the structure variously known as cond, when, match, etc. If you can only have one, by all means, take the cond, it will be useful more often, but switch's computed goto is a very useful thing to have in reserve.

crimsonalucard7• 8 years ago

While C++ had similar goals, it has the disadvantages of multiple legacy design-choices (e.g., object-oriented)

How many people agree with this statement? OO is a legacy design choice or in other words: a bad design choice.

I agree with the statement, so do most modern languages like rust and golang but I wonder what do non language designers think? This statement was given as if it was obvious but many programmers who I work with still think OO is the greatest invention ever.

seabrookmx4• 8 years ago

I think OO bashing is just another trendy comment people make. I find it really hypocritical, because the same people that will bash OO in a thread like this will rave about how nice it is to write Python, or are giddy about the latest ES6+ features. Both Python and ES6 have class-based OO, and it is used to great benefit every day.

OO can _definitely_ be misused and I think the disconnect is that the traditional abuses of OO (deep class hierarchies, fragile base classes, etc) are associated to "oldschool" Java and C++ codebases. But if developers followed the "composition over inheritance" mantra back then, maybe this complaint wouldn't be so prevalent.

I pretty fluidly move between Typescript/C#/GoLang and after the initial hump in GoLang, I find I don't have much preference. Some code feels more clunky without "traditional" OO and some feels better. I've yet to really dive into traits in Rust but I'm guessing I'll feel the same way when I get around to it.

crimsonalucard7• 8 years ago

Mantras decrying a built in feature of OO are just flaws within the paradigm.

I don't think it's trendy if newer next generation languages like go rust and nim avoid OO. These experts who design languages know something.

pjmlp29• 8 years ago

Go and Rust are also OO.

There isn't such thing as the only true and single way of doing OOP.

Also without OOP, good luck doing GUI programming in C++. Even Motif and GTK+ are OOP based, in C, because immediate UIs suck for anything beyond simple game UIs.

BruceIV17• 8 years ago

[on the Cforall team] FWIW, the Go docs are somewhat ambivalent on the OO nature of Go[1]. Along similar lines, our main objections to object-orientation are that, in "traditional" implementations like C++ or Java, it tightly couples a number of features that we believe would be better served by a more orthogonal design.

More specifically, C++-style OO couples (1) in-memory layout of types, (2) behaviour of objects, (3) encapsulation boundaries, and (4) the hierarchical "is-a" relationship. In Cforall, (1) and (3) are handled by the usual C mechanisms of struct types and translation-unit boundaries [we go to great effort to maintain C-style separate compilation, though we will likely build a better namespace/module system at some point], (2) by traits, and (4) by a yet-to-be-implemented system of RTTI for specific "inherited" types [likely when the undergrad RA who started our exceptions implementation comes back as a Master's student this fall].

As you mention, many use-cases (including widgets in GUIs, but also abstract syntax trees in compilers) require some sort of heterogeneous collection type to work properly, and for this OO is the right model. We just don't want to force the entirety of that model on every use case, so we can just take traits when we want to write a polymorphic function over related types or an ADT like "Set" which requires its keys be sortable, or just take RTTI for exception handling, when the set of exception types we're handling is known statically, but we need to determine if the thrown exception inherits from one of the caught types.

[1] https://golang.org/doc/faq#Is_Go_an_object-oriented_language

crimsonalucard7• 8 years ago

Modern GUIs happen mostly in JavaScript with the react + redux ecosystem which is more of a functional model then OO.

quelsolaar• 8 years ago

This is the wrong way to go about it. The syntax is great, what is needed is updates to reflect modern hardware:

-Vector types. (With arbitrary sizes not just up to vec4 for like on GPUs)

-New operators like clamp, and other intrinsic. (See GLSL and modern instruction sets)

-Min/max: |< >|

-Dot:

-Cross product: ><

-Swizzle: a.3.2.1.0

-Qualifiers for warping behavior.

-Standard library with cash management hints.

-Define qualifiers for padding of structs to be defined.

I would also argue you could change some things in the spec to make it easier for compilers to optimize, like making the calling a switch without a catching case undefined behavior.

As for the syntax itself, I could find being able to type multiple break commands in a row to get out of more then one loop useful, but its not a big thing.

I would probably drastically restrict the power of the pre-processor too.

(If you have too much time on your hands: https://www.youtube.com/watch?v=443UNeGrFoM)

irundebian• 8 years ago

Please smart people, spent your intelligence on clean approaches such as memory-safe system programming languages such as Rust or so instead of wasting time with old broken legacy languages. I want to see secure systems before I die.

antirez3• 8 years ago

I studied the documentation, basically 80 percent of what is added is not what is needed for C to become better, in my opinion.

kosma• 8 years ago

Thousand times this. C for All is "what the language researchers want", not "what the C users need".

msaltz• 8 years ago

In my opinion, what C is lacking isn’t primarily language features - it’s: 1) a common, readable style standard that people can agree on 2) modern agreed-upon idiomatic ways to write readable and safe code. There are certainly common C idioms but many exist for historical reasons and not because they’re necessarily the best things to do, and 3) a standard library that exemplifies the above two things, provides common functionality needed between projects, and fosters a sense of community

Efforts like those of the poster don’t really address these things.

When I tell people I like C, the response differs depending on experience level. Less experienced people who haven’t spent time in C++ either will say “Gross, pointers”. People used to C++ will say “what about templates and constructors/destructors”, and “are you going to write your own library for vectors and maps every time?” And people who are experienced (more experienced than me) and like C have generally said that the main things they miss from C++ are constructors and destructors (and mostly destructors), and templates (but only for container types), but that they can live without them.

C is a small language that can be relatively easy to write (once you pick/write a suitable stl-equivalent), and extremely easy to read (and to the extent that you can look at a line and know exactly what’s going on under the hood). IMO it should stay that way.

Take a look at zproject [0] for what I think is a good effort to standardize C style and project structure. Even if you disagree with the particular design choices, the spirit of it is what I think is needed to keep people from just assuming C is for dinosaurs.

[0] https://github.com/zeromq/zproject/

sanbor2• 8 years ago

I have little experience with C but my feeling is that it's a waste of time to have to deal with memory in my program.

I don't just have to worry about the problem that I'm trying to solve but also about handling the memory properly.

Of course there are scenarios where writing a fast and lightweight app is part of the problem but for many projects that's not the case.

I'm fine with pointer arithmetic and all that but I'm not fine with the constant fear that I did some oversight and my app is going to crash and I'll have to spend time debugging what's going on.

Retra2• 8 years ago

Most programming problems are pretty trivial to solve if you're willing to ignore performance. It behooves us to realize that the main difference between mathematics and computer science is that computer scientists have to account for the several orders of magnitude difference between the runtime costs of different operations. If that weren't an obstacle, we'd basically only need one programming language, and it would like pretty much like standard mathematics.

So I interpret your comment as something like "I don't want to program, I just want to assemble mathematical statements", which is a fine and perfectly legitimate thing to do, but it also seems a bit lazy, impractical, and probably irrelevant, given the subject.

jacknews• 8 years ago

I agree. The proposal adds a bunch of ugly and unnecessary syntax without addressing any of the real issues with C

gcbw2• 8 years ago

Should have fixed the easier problem first. The 'searchability' of the language name.

BruceIV17• 8 years ago

[on the team] It helps if you use the official ASCII spelling, Cforall -- a DuckDuckGo search for "Cforall" in private browsing mode pulled up our homepage first result. (I have no idea who the OP for this thread is, they're no one associated with the team.)

throwaway45074• 8 years ago

The (draft) ISO C11 spec is already nearly 700 pages[1]. How can anyone justify adding something like "choose" (a switch() without fall-throughs) to such a language?

Who are these people[2], and what is their mandate? Did they actually consult with the likes of Linus Torvalds, Greg KH, Mike Pall--those who actually use C every single day on mission-critical projects like OS kernels and virtual machines--and ask them what improvements to C they need?

1) http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf

2) https://plg.uwaterloo.ca/~cforall/people

joshuak• 8 years ago

I've had renewed interest in C recently, having been away from it for nearly 10 years. This renewed interest comes from working with golang for the last few years, and has caused me to find this book[0] which discusses ways to implement OOP ideas in pure C. Not to promote Go, or OOP, but rather I wonder if selecting useful idioms form modern languages wouldn't be a better intermediate step to updating C, then language level changes.

[0] https://www.cs.rit.edu/~ats/books/ooc.pdf

Ericson2314• 8 years ago

This is stupid. C accepts too many programs already. Rust mainly improves by accepting fewer. The few compatability-breaking changes this includes don't go far enough to matter.

enriquto3• 8 years ago

A beautiful, and simple, addition to the C language would be a mechanism to assess the remaining stack size. This is trivial to check in assembler, but practically impossible in portable C.

Indeed, thanks to VLA, the stack can be used as a clean notation for raii. You just replace this ugly, but very common, construction

    void f(int n)
    {
            float *x = malloc(n * sizeof*x);
            // ...
            free(x);
    }

with this

    void f(int n)
    {
            float x[n];
            // ...
    }

BruceIV17• 8 years ago

[on the Cforall team] we actually take advantage of this same VLA idiom for temporary storage for polymorphic variables.

Fun fact from when we switched our implementation to use VLAs: if you call alloca() for stack memory instead, it doesn't work properly inside a loop, because it never releases the memory until the stack frame is exited.

pjmlp29• 8 years ago

VLAs were made optional in C11 as they became yet another security exploit vector, and not all C vendors are keen in supporting it, especially on the embedded space.

coldtea• 8 years ago

The biggest evolution for C, to cut down bugs to 1/10 would be to have a proper built-in string type -- one that easily transforms into the relevant C type, and that keeps the size.

(And maybe a vector and hashmap).

earenndil4• 8 years ago

sds? https://github.com/antirez/sds

luckydude• 8 years ago

Hmm, we took a different approach, here's my C-like dialect (built on Tcl's byte codes so it co-exists with Tcl code. And yes, I know, but we needed Tk so were stuck with Tcl).

http://little-lang.org

Stuff that I'd like to C in an evolved C:

regexp engine as part of the language so you can do

    while (buf = <>) if (buf =~ /some regexp/) puts(buf);

<> and <FD> from perl, just handy.

Lists as a built in, with any element type and builtins like push, pop, shift, unshift, etc. Again, more perl goodness without all the @'s and $'s.

${expr} interpolation inside strings. Like shell, and it's handy.

At this point I'm just typing in the L language docs, so most of the stuff here:

http://www.little-lang.org/little.html

BTW - the logo for the language is a tip of the hat to the things that inspired it: the Tcl feather logo, the Perl camel logo, and "C" all bunched together. I'm very fond of that logo but not sure that anyone but me gets it.

halfer53• 8 years ago

I'm personally in favour of this proposal, I'm sick of having to write function pointer when implementing objects in C. Looking forward to seeing this in the next C standard

C for All

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