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I'm always slightly confused when languages target C instead of compiling themselves. Nim, for example. Is it really that much easier to deal with all the idios

by chc4 11y ago

I'm always slightly confused when languages target C instead of compiling themselves. Nim, for example. Is it really that much easier to deal with all the idiosyncrasies of C for a backend, and have to hope that the compiler will cleanup the mass of basic code blocks you emit, than emit LLVM bytecode or assembly? Not even having to use the LLVM C bindings, you can just emit the bytecode directives to a file and call the toolchain itself. Is the idea that you can compile you base code once, and then work on the emitted C to extend the project?

camgunz 11y ago
I've heard portability arguments; C is far more portable than LLVM. But I'm guessing more people know C than LLVM IR or 4 assembly languages, so C is an easier target. EDIT: oh, also wildly easy interoperability with existing C/C++ code (so long as the C++ code provides a C interface).
- dom96 11y ago
  Compiling down to C also makes wrapping C++ libraries much easier. Because when you compile down to C, it's not that much of a stretch to also allow compilation to C++. You can then make wrapping C++ code much easier in the language. Nim is one language that I know of which takes advantage of that. Here is one example of a pretty large wrapper around a C++ library https://github.com/3dicc/Urhonimo https://github.com/3dicc/Urhonimo, and here is the documentation for this feature http://nim-lang.org/docs/manual.html#implementation-specific-pragmas-importcpp-pragma http://nim-lang.org/docs/manual.html#implementation-specific...
sanxiyn 11y ago
In this particular case, ooc is a syntax sugar for C, like CoffeeScript is a syntax sugar for JavaScript. It wouldn't make any sense not to compile to C.
- theseoafs 11y ago
  Coffeescript compiles to JavaScript for a reason though. No language ever has a reason to compile to C unless your platform is really goofy.
ziotom78 11y ago
As camgunz said, emitting C code makes your compiler far more portable, as you can find C compilers for virtually every target (e.g., AFAIK, the current version of LLVM does not support SPARC architectures). Another theoretical advantage of generating C code is that it should be easy to try adding bits of code written in these new languages to existing C/C++ projects. In this way you can test the new language on real life projects without the need of rewriting everything from scratch. (I have never followed this approach, although I have heard of people having done this [1].) [1] http://roscidus.com/blog/blog/2014/06/06/python-to-ocaml-retrospective/ http://roscidus.com/blog/blog/2014/06/06/python-to-ocaml-ret... The languages here were quite different, though (Python/OCaml): but the author followed the idea of slowly converting a project to a new language by first rewriting parts of it. Had the OCaml compiler emitted Python code, I bet the task would have been easier.
jarcane 11y ago
Depending on the C standard you're emitting, portability and backward compatibility gains can potentially be huge. I've even occasionally managed to get code from compiled-to-C languages working on platforms like RiscOS and Amiga.
vardump 11y ago
You can often use any language for esoteric microcontrollers, as long as it's C. Languages that can be compiled to C could be interesting for implementing embedded system firmware.
beagle3 11y ago
LLVM bitcode is version dependent. Some of it is architecture dependent. Emitting C is way way easier.
gizmo 11y ago
I think the biggest benefit of compiling to C is that you can output comments about which C sections correspond to which lines in the higher level code, and then you can use step-through debuggers to see why your emitted code isn't working right. You don't have to deal with all the idiosyncrasies of C, because you can restrict yourself to a small subset of C that is straightforward and easily understood.
cobaltblue 11y ago
Odd to see it not mentioned as another benefit, but by targeting C instead of say direct assembly you benefit from the decades of optimization research that has gone into modern C compilers.

by chc4 11y ago

camgunz 11y ago

I've heard portability arguments; C is far more portable than LLVM. But I'm guessing more people know C than LLVM IR or 4 assembly languages, so C is an easier target. EDIT: oh, also wildly easy interoperability with existing C/C++ code (so long as the C++ code provides a C interface).

dom96 11y ago
Compiling down to C also makes wrapping C++ libraries much easier. Because when you compile down to C, it's not that much of a stretch to also allow compilation to C++. You can then make wrapping C++ code much easier in the language. Nim is one language that I know of which takes advantage of that. Here is one example of a pretty large wrapper around a C++ library https://github.com/3dicc/Urhonimo https://github.com/3dicc/Urhonimo, and here is the documentation for this feature http://nim-lang.org/docs/manual.html#implementation-specific-pragmas-importcpp-pragma http://nim-lang.org/docs/manual.html#implementation-specific...

sanxiyn 11y ago

In this particular case, ooc is a syntax sugar for C, like CoffeeScript is a syntax sugar for JavaScript. It wouldn't make any sense not to compile to C.

theseoafs 11y ago
Coffeescript compiles to JavaScript for a reason though. No language ever has a reason to compile to C unless your platform is really goofy.

ziotom78 11y ago

As camgunz said, emitting C code makes your compiler far more portable, as you can find C compilers for virtually every target (e.g., AFAIK, the current version of LLVM does not support SPARC architectures). Another theoretical advantage of generating C code is that it should be easy to try adding bits of code written in these new languages to existing C/C++ projects. In this way you can test the new language on real life projects without the need of rewriting everything from scratch. (I have never followed this approach, although I have heard of people having done this [1].) [1] http://roscidus.com/blog/blog/2014/06/06/python-to-ocaml-retrospective/ http://roscidus.com/blog/blog/2014/06/06/python-to-ocaml-ret... The languages here were quite different, though (Python/OCaml): but the author followed the idea of slowly converting a project to a new language by first rewriting parts of it. Had the OCaml compiler emitted Python code, I bet the task would have been easier.

jarcane 11y ago

Depending on the C standard you're emitting, portability and backward compatibility gains can potentially be huge. I've even occasionally managed to get code from compiled-to-C languages working on platforms like RiscOS and Amiga.

vardump 11y ago

You can often use any language for esoteric microcontrollers, as long as it's C. Languages that can be compiled to C could be interesting for implementing embedded system firmware.

beagle3 11y ago

LLVM bitcode is version dependent. Some of it is architecture dependent. Emitting C is way way easier.

gizmo 11y ago

I think the biggest benefit of compiling to C is that you can output comments about which C sections correspond to which lines in the higher level code, and then you can use step-through debuggers to see why your emitted code isn't working right. You don't have to deal with all the idiosyncrasies of C, because you can restrict yourself to a small subset of C that is straightforward and easily understood.

cobaltblue 11y ago

Odd to see it not mentioned as another benefit, but by targeting C instead of say direct assembly you benefit from the decades of optimization research that has gone into modern C compilers.