7 ms·

C2 Lang design (2014) [pdf]

41 points by asaka 11y ago

yoklov 11y ago
Looks extremely interesting. I'm skeptical of some of its claims (faster compilation when incremental compilation is removed sounds unlikely, for example), but nothing that worrisome. Anybody have any experience? Is it still basically a toy language?
- aidenn0 11y ago
  The main site makes it look like the language is about a year old. I have no doubt that they can make the parsing stage faster, as they won't be parsing the same headers over and over again. This is often a bottleneck in C++, but much less often in C. (I've seen 10+MB C++ files after preprocessing).
  - buserror 11y ago
    If people used precompiled headers (which have been available for about 20 years) that problem wouldn't be there... However I'm not sure that the parsing is such a bottleneck these days; I think all the complex constructs are a lot more of a time sink (templates etc). That and linking! Takes an hour to link the webkit library with the regular linker :-)
    - aidenn0 11y ago
      It's been a while since I tried precompiled headers, but the last time I tried it, the experience was unpleasant and error-prone.
bluejekyll 11y ago
Is there an advantage to this over say a more modern and safe language like Rust? It seems to be just reducing the complexity of the language, but doesn't look like it will reduce memory related bugs.
- rwmj 11y ago
  Since you have to rewrite everything, you might as well switch to another language (we switched to OCaml). If there was an incremental path or a safe subset of C or something like that, that would be more interesting.
  - qznc 11y ago
    You can use D, which shares a lot of syntax with C, although you cannot directly reuse C code because there is no preprocessor in D. Some people use D as a "C development compiler". The incremental path is the official C standards. C will probably gain modules for example.
    - rwmj 11y ago
      In the project I'm working on right now, there are 277,617 lines of C (using gcc extensions). The incremental path either compiles all of that directly, or we rewrite it. There's hardly any middle ground, and actually rewriting it isn't a realistic option either. (For comparison the same project has 63,972 lines of OCaml and 31,605 lines of Perl)
  - tempodox 11y ago
    My thoughts exactly. If nothing bad happens, I think Rust will be a worthy successor of C in low-level land. If I need a higher abstraction level, I use either Lisp if I want dynamic typing, or OCaml if I want static typing. Together, those three cover a vast spectrum. addendum: That doesn't mean C2 is not a worthwhile experiment. I might even try it out when a compiler is available.
  - steveklabnik 11y ago
    We have pretty good C interop, so you don't have to re-write everything, you can do it in chunks. Firefox isn't suddenly going to be reimplemented in Rust, for example, it will be library by library, bit by bit. Of course, you can do that with some other languages too, but our lack of runtime and no-overhead makes it significantly better, in my opinion.
jeffreyrogers 11y ago
This is cool. I've often toyed with a similar idea of creating a language that improves/fixes the thing C messed up. If you aren't worried about safety (memory bugs can largely be avoided by changing how you do memory allocation, i.e. switch from individual mallocing to region based memory management) then C is actually a pretty nice language since it is simple enough to hold the entire language in your head. Plus it's nice to know how things are actually laid out in memory. The problems C2 solves are really the main things that frustrate me about C: header files, lack of a build systems, no modules, spiraling type signatures.
xamuel 11y ago
Thoughts as I read: 1. "uninitialized var usage is error": unfortunately impossible without at least one of the following compromises: Automatically initialize variables (wastes CPU); False alarms (see Java); Built-in formal proof system; or, Require compilers to solve the halting problem. 2. Removed keyword "static": kills one of my favorite tricks, "self-init'ing functions". 3. New keyword "as": A good invention in Pythonland. Good call to bring this in. 4. New keyword "nil": Redundant with NULL? 5. Example - Base Types: Uses uint8 in place of char. This obscures intent and makes code less readable. Compare: int library_fnc(char asterisk errmsg) versus int library_fnc(uint8 asterisk errmsg). (HN wants to turn my asterisks into italics...) In the former it's clear errmsg is a string, in the latter it's not clear (it could be a pointer to a flag). 6. Example - function types. Doesn't one usually typedef the function pointer, rather than the function itself? So making that require two lines is annoying. Aside that, the author is right that C has confusing function pointer typedef syntax. 7. Multi-part array initialization: Encourages unmaintainable code. Depending on what's in those "..."'s, might require compiler to solve halting problem? 8. Multi-pass parsing: Trades maintainability for instant gratification. 9. Symbol accessibility: The author makes "public" (and implicit "private") modify entire structs rather than individual fields... 10. Multi-file module: May lead to unmaintainable code 11. I'm worried about the language arbitrarily defining things like "the results of building are stored in the 'output' directory". OTOH the recipe.txt idea could help standardize what amounts to a lot of ad hoc Makefile programming. 12. Build process difference: Theoretically could speed up compilation. I'm worried for social reasons. In module-based languages, we tend to fall into module hell: one symptom being the infamous 20-page stacktrace (see: Java, Clojure, etc.) The nature of C's #include incentivizes shallow dependency trees (a very good thing). 13. "Language scope": trades portability for convenience 14. Tooling: This shouldn't be part of the language, it should be separate.
- xyzzyz 11y ago
  5. Example - Base Types: Uses uint8 in place of char. This obscures intent and makes code less readable. Compare: int library_fnc(char asterisk errmsg) versus int library_fnc(uint8 asterisk errmsg). (HN wants to turn my asterisks into italics...) In the former it's clear errmsg is a string, in the latter it's not clear (it could be a pointer to a flag). You can always typedef it if you want it. The point is that naming a basic numeric type "char" is not only confusing, but also wrong in the world that's no longer all ASCII.
felixangell 11y ago
Very similar to Ark: www.github.com/ark-lang/ark. Except Ark has no GC, has tagged enums, ownership is enforced, and a few other smaller differences.
b3h3moth 11y ago
There is a Standard ISO committee (JTC1/SC22/WG14) - for that, please!
adrusi 11y ago
I understand why it's attractive to integrate more and more into the language proper, but I don't like it. Almost all tools which still embrace the unix way of doing things are written in C, and it's not just because that community is conservative. C feels like unix, because it's one of the only languages that abides by that philosophy. C-the-language is only part of the experience of programming in C. Programming in C includes DSLs and code generation and makefiles. Even what we consider C-the-language can be decomposed into preprocessor code and actual C. That said, C needs to be improved, but I think it should be done via the build system, adding layers on top of C, in a tasteful, thought-out way. Some ideas below: If we're expanding on C by adding build system complexity, Makefiles need to be improved. Make is a great tool, but it's unityped, like shell scripts. And it's essentially a preprocessor over shell, which leads to a mess of sigils. Maybe redesigning make as an embedded language in some lisp would do it. Additionally we could unify the notion of linking to a library and importing code into the makefile to allow dependencies to specify build steps. This could make some of the added build complexity implicit. Namespaces could probably be implemeneted as a preprocessor, taking module declarations and import statements and converting all identifiers into they prefix qualified equivalents, emiting warnings when there would be a collision (like if module "foo" declared "bar_baz" and module "foo_bar" declared "baz"). Rust-style syntax-case macros can be implemented as a preprocessor. Go-style defer statements could be implemented in a preprocessor, and avoid the somewhat verbose goto-style error handling. As I said, this approach requires a lot of care to avoid adding a huge amount of complexity to the language.

41 points by asaka 11y ago

Looks extremely interesting. I'm skeptical of some of its claims (faster compilation when incremental compilation is removed sounds unlikely, for example), but nothing that worrisome. Anybody have any experience? Is it still basically a toy language?

aidenn0 11y ago
The main site makes it look like the language is about a year old. I have no doubt that they can make the parsing stage faster, as they won't be parsing the same headers over and over again. This is often a bottleneck in C++, but much less often in C. (I've seen 10+MB C++ files after preprocessing).
- buserror 11y ago
  If people used precompiled headers (which have been available for about 20 years) that problem wouldn't be there... However I'm not sure that the parsing is such a bottleneck these days; I think all the complex constructs are a lot more of a time sink (templates etc). That and linking! Takes an hour to link the webkit library with the regular linker :-)
  - aidenn0 11y ago
    It's been a while since I tried precompiled headers, but the last time I tried it, the experience was unpleasant and error-prone.

bluejekyll 11y ago

Is there an advantage to this over say a more modern and safe language like Rust? It seems to be just reducing the complexity of the language, but doesn't look like it will reduce memory related bugs.

rwmj 11y ago
Since you have to rewrite everything, you might as well switch to another language (we switched to OCaml). If there was an incremental path or a safe subset of C or something like that, that would be more interesting.
- qznc 11y ago
  You can use D, which shares a lot of syntax with C, although you cannot directly reuse C code because there is no preprocessor in D. Some people use D as a "C development compiler". The incremental path is the official C standards. C will probably gain modules for example.
  - rwmj 11y ago
    In the project I'm working on right now, there are 277,617 lines of C (using gcc extensions). The incremental path either compiles all of that directly, or we rewrite it. There's hardly any middle ground, and actually rewriting it isn't a realistic option either. (For comparison the same project has 63,972 lines of OCaml and 31,605 lines of Perl)
- tempodox 11y ago
  My thoughts exactly. If nothing bad happens, I think Rust will be a worthy successor of C in low-level land. If I need a higher abstraction level, I use either Lisp if I want dynamic typing, or OCaml if I want static typing. Together, those three cover a vast spectrum. addendum: That doesn't mean C2 is not a worthwhile experiment. I might even try it out when a compiler is available.
- steveklabnik 11y ago
  We have pretty good C interop, so you don't have to re-write everything, you can do it in chunks. Firefox isn't suddenly going to be reimplemented in Rust, for example, it will be library by library, bit by bit. Of course, you can do that with some other languages too, but our lack of runtime and no-overhead makes it significantly better, in my opinion.

jeffreyrogers 11y ago

This is cool. I've often toyed with a similar idea of creating a language that improves/fixes the thing C messed up. If you aren't worried about safety (memory bugs can largely be avoided by changing how you do memory allocation, i.e. switch from individual mallocing to region based memory management) then C is actually a pretty nice language since it is simple enough to hold the entire language in your head. Plus it's nice to know how things are actually laid out in memory. The problems C2 solves are really the main things that frustrate me about C: header files, lack of a build systems, no modules, spiraling type signatures.

xamuel 11y ago

Thoughts as I read: 1. "uninitialized var usage is error": unfortunately impossible without at least one of the following compromises: Automatically initialize variables (wastes CPU); False alarms (see Java); Built-in formal proof system; or, Require compilers to solve the halting problem. 2. Removed keyword "static": kills one of my favorite tricks, "self-init'ing functions". 3. New keyword "as": A good invention in Pythonland. Good call to bring this in. 4. New keyword "nil": Redundant with NULL? 5. Example - Base Types: Uses uint8 in place of char. This obscures intent and makes code less readable. Compare: int library_fnc(char asterisk errmsg) versus int library_fnc(uint8 asterisk errmsg). (HN wants to turn my asterisks into italics...) In the former it's clear errmsg is a string, in the latter it's not clear (it could be a pointer to a flag). 6. Example - function types. Doesn't one usually typedef the function pointer, rather than the function itself? So making that require two lines is annoying. Aside that, the author is right that C has confusing function pointer typedef syntax. 7. Multi-part array initialization: Encourages unmaintainable code. Depending on what's in those "..."'s, might require compiler to solve halting problem? 8. Multi-pass parsing: Trades maintainability for instant gratification. 9. Symbol accessibility: The author makes "public" (and implicit "private") modify entire structs rather than individual fields... 10. Multi-file module: May lead to unmaintainable code 11. I'm worried about the language arbitrarily defining things like "the results of building are stored in the 'output' directory". OTOH the recipe.txt idea could help standardize what amounts to a lot of ad hoc Makefile programming. 12. Build process difference: Theoretically could speed up compilation. I'm worried for social reasons. In module-based languages, we tend to fall into module hell: one symptom being the infamous 20-page stacktrace (see: Java, Clojure, etc.) The nature of C's #include incentivizes shallow dependency trees (a very good thing). 13. "Language scope": trades portability for convenience 14. Tooling: This shouldn't be part of the language, it should be separate.

xyzzyz 11y ago
5. Example - Base Types: Uses uint8 in place of char. This obscures intent and makes code less readable. Compare: int library_fnc(char asterisk errmsg) versus int library_fnc(uint8 asterisk errmsg). (HN wants to turn my asterisks into italics...) In the former it's clear errmsg is a string, in the latter it's not clear (it could be a pointer to a flag). You can always typedef it if you want it. The point is that naming a basic numeric type "char" is not only confusing, but also wrong in the world that's no longer all ASCII.

felixangell 11y ago

Very similar to Ark: www.github.com/ark-lang/ark. Except Ark has no GC, has tagged enums, ownership is enforced, and a few other smaller differences.

b3h3moth 11y ago

There is a Standard ISO committee (JTC1/SC22/WG14) - for that, please!

adrusi 11y ago

I understand why it's attractive to integrate more and more into the language proper, but I don't like it. Almost all tools which still embrace the unix way of doing things are written in C, and it's not just because that community is conservative. C feels like unix, because it's one of the only languages that abides by that philosophy. C-the-language is only part of the experience of programming in C. Programming in C includes DSLs and code generation and makefiles. Even what we consider C-the-language can be decomposed into preprocessor code and actual C. That said, C needs to be improved, but I think it should be done via the build system, adding layers on top of C, in a tasteful, thought-out way. Some ideas below: If we're expanding on C by adding build system complexity, Makefiles need to be improved. Make is a great tool, but it's unityped, like shell scripts. And it's essentially a preprocessor over shell, which leads to a mess of sigils. Maybe redesigning make as an embedded language in some lisp would do it. Additionally we could unify the notion of linking to a library and importing code into the makefile to allow dependencies to specify build steps. This could make some of the added build complexity implicit. Namespaces could probably be implemeneted as a preprocessor, taking module declarations and import statements and converting all identifiers into they prefix qualified equivalents, emiting warnings when there would be a collision (like if module "foo" declared "bar_baz" and module "foo_bar" declared "baz"). Rust-style syntax-case macros can be implemented as a preprocessor. Go-style defer statements could be implemented in a preprocessor, and avoid the somewhat verbose goto-style error handling. As I said, this approach requires a lot of care to avoid adding a huge amount of complexity to the language.