5 ms·

The C-- Language Specification (2005) [pdf]

103 points by headalgorithm 8y ago

tyingq 8y ago
Short overview of "C--" : https://www.cs.tufts.edu/~nr/c--/index.html https://www.cs.tufts.edu/~nr/c--/index.html
blacksqr 8y ago
Code at: https://github.com/nrnrnr/qc-- https://github.com/nrnrnr/qc--
- vmchale 8y ago
  Very neat, thank you!
afraca 8y ago
A prominent project where I have encountered this is GHC, the Haskell compiler. The route there goes: Haskell --> Core --> STG --> C-- (It then goes to one of: - Machine code generation - into C for feeding to gcc - into LLVM's intermediate representation. )
- faissaloo 8y ago
  Would converting C-- to C/LLVM IR be redundant?
  - kryptiskt 8y ago
    It's true that they are mostly on the same level but it's way easier to compile C-- to LLVM IR or C than to write three separate STG->(Imperative code) stages.
- YorkshireSeason 8y ago
  For those who are not Haskell experts, Core is a small lambda-calculus with case (pattern matching), let and coercions, see [1] for details. STG stands for Spineless-Tagless G-machine and is a refinement of the older G-machine. The G-machine (short for Graph-Reduction Machine) is for the lazy (call-by-need) evaluation of functional programs in supercombinator form [4]. Instead of interpreting supercombinators as rewrite rules, they were compiled into sequential code with special instructions for graph manipulation. See [2]. For a general overview of GHC's architecture, see [3]. [1] A. Tolmach, T. Chevalier and the GHC Team, An External Representation for the GHC Core Language (For GHC 6.10). https://downloads.haskell.org/~ghc/6.12.2/docs/core.pdf https://downloads.haskell.org/~ghc/6.12.2/docs/core.pdf [2] S. Peyton Jones, Implementing lazy functional languages on stock hardware: the Spineless Tagless G-machine. https://www.microsoft.com/en-us/research/wp-content/uploads/1992/04/spineless-tagless-gmachine.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/... [3] S. Marlow, S. Peyton-Jones, The Glasgow Haskell Compiler. https://www.aosabook.org/en/ghc.html https://www.aosabook.org/en/ghc.html [4] https://wiki.haskell.org/Super_combinator https://wiki.haskell.org/Super_combinator
dragonbonheur 8y ago
The other project named C-- http://c--sphinx.narod.ru/indexe.htm http://c--sphinx.narod.ru/indexe.htm
- ginko 8y ago
  At least that one actually defines a decrement operator.
- vgoh1 8y ago
  I used this in the mid- to late-90's on my 80386 (which was very much out of date at the time, but was all I had). I was very new to computing at the time, and the only other languages that I had under my belt were QuickBASIC and 80386 assembler, so I can't comment on if it were a "good" language or not. After less than a year, I ended up abandoning it, preferring to use QuickBASIC for high level, and machine language for low, not feeling like I needed the intermediate C--.
ThePadawan 8y ago
IIRC EiffelStudio compiled Eiffel to C-- as an intermediary stage, but I haven't used it since university and struggle to find information about that online.
- _pmf_ 8y ago
  Slightly off topic: did you do any projects using Eiffel, and if yes, what were the benefits / unique features?
  - ThePadawan 8y ago
    I did not use it past university.
carterschonwald 8y ago
There’s an alternative timeline where c— was better marketed / promulgated as a backend tool kit for optimizing compilers and everyone use c— instead. That’s not to say llvm isn’t great, but some of the design choices it has make it a lot of work to do funky stuff ! And c— is a bit easier to write low level rts snippets in. I do think the ghc c— flavor is super nice to write in these days.
metalliqaz 8y ago
Sometime in the 90's I downloaded a programming language called "C--" that was basically assembly with some loop control structures and functions. I'm assuming this completely unrelated. Edit: ah, looks like dragonbonheur found and linked it already in this thread!
- sprinx 8y ago
  That was Sprinkx C-- Great Compiller with IDE in late 90's http://c--sphinx.narod.ru/indexe.htm http://c--sphinx.narod.ru/indexe.htm
gnulinux 8y ago
Does compiling to C-- have any benefits compared to compiling equivalent C code (maybe a subset of C)? My guess would be modern C compilers, powered by decades of R&D and programming, would be able to optimize just as well and possibly better. EDIT: One advantage that comes to my mind is that compiling to C-- will give slightly more power to deal with stack. E.g. implementing exceptions, continuations etc would be simpler. This is possible in C using inline assembly.
- vmchale 8y ago
  >My guess would be modern C compilers, powered by decades of R&D and programming, would be able to optimize just as well and possibly better. GHC often produces more efficient code than the LLVM backend.
- ufo 8y ago
  Another thing it helps with is garbage collection. If you compile down to C it also requires stack trickery.
- rwhaling 8y ago
  One benefit that is repeatedly mentioned in the papers is the ability to do tail-call optimization, which is more or less impossible with compile-to-c interpretations, and mandatory for functional languages.
vmchale 8y ago
Is GHC the only project that uses this?
ufo 8y ago
Are there any projects other than GHC which still use C--? I had heard that it was unfortunately kind of dead these days.
tempodox 8y ago
This looks like a precursor of LLVM IR.
inspector-g 8y ago
Interesting! I've been writing a lot of C/C++ for over a decade, but had never heard of C-- before. So, I went to the website[1] linked in the PDF to learn more, but sadly it appears the domain has been taken over and now just displays a small collection of badly written articles about Windows. [1] http://cminusminus.org http://cminusminus.org
DonHopkins 8y ago
Generalizing Overloading for C++2000: Bjarne Stroustrup, AT&T Labs, Florham Park, NJ, USA. Abstract: This paper outlines the proposal for generalizing the overloading rules for Standard C++ that is expected to become part of the next revision of the standard. The focus is on general ideas rather than technical details (which can be found in AT&T Labs Technical Report no. 42, April 1,1998). http://www.stroustrup.com/whitespace98.pdf http://www.stroustrup.com/whitespace98.pdf
DonHopkins 8y ago
C++++-= “C++++-= is the new language that is a little more than C++ and a lot less.” -Bill Joy In this talk from 1991, Bill Joy predicts a new hypothetical language that he calls “C++++-=”, which adds some things to C++, and takes away some other things. https://medium.com/@donhopkins/bill-joys-law-2-year-1984-million-instructions-per-second-3a8c92165cfe https://medium.com/@donhopkins/bill-joys-law-2-year-1984-mil...
evincarofautumn 8y ago
I would love to use it for my compiler backend…if I could find any maintained standalone implementations of it.

103 points by headalgorithm 8y ago

tyingq 8y ago

Short overview of "C--" : https://www.cs.tufts.edu/~nr/c--/index.html https://www.cs.tufts.edu/~nr/c--/index.html

blacksqr 8y ago

Code at: https://github.com/nrnrnr/qc-- https://github.com/nrnrnr/qc--

vmchale 8y ago
Very neat, thank you!

afraca 8y ago

A prominent project where I have encountered this is GHC, the Haskell compiler. The route there goes: Haskell --> Core --> STG --> C-- (It then goes to one of: - Machine code generation - into C for feeding to gcc - into LLVM's intermediate representation. )

faissaloo 8y ago
Would converting C-- to C/LLVM IR be redundant?
- kryptiskt 8y ago
  It's true that they are mostly on the same level but it's way easier to compile C-- to LLVM IR or C than to write three separate STG->(Imperative code) stages.
YorkshireSeason 8y ago
For those who are not Haskell experts, Core is a small lambda-calculus with case (pattern matching), let and coercions, see [1] for details. STG stands for Spineless-Tagless G-machine and is a refinement of the older G-machine. The G-machine (short for Graph-Reduction Machine) is for the lazy (call-by-need) evaluation of functional programs in supercombinator form [4]. Instead of interpreting supercombinators as rewrite rules, they were compiled into sequential code with special instructions for graph manipulation. See [2]. For a general overview of GHC's architecture, see [3]. [1] A. Tolmach, T. Chevalier and the GHC Team, An External Representation for the GHC Core Language (For GHC 6.10). https://downloads.haskell.org/~ghc/6.12.2/docs/core.pdf https://downloads.haskell.org/~ghc/6.12.2/docs/core.pdf [2] S. Peyton Jones, Implementing lazy functional languages on stock hardware: the Spineless Tagless G-machine. https://www.microsoft.com/en-us/research/wp-content/uploads/1992/04/spineless-tagless-gmachine.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/... [3] S. Marlow, S. Peyton-Jones, The Glasgow Haskell Compiler. https://www.aosabook.org/en/ghc.html https://www.aosabook.org/en/ghc.html [4] https://wiki.haskell.org/Super_combinator https://wiki.haskell.org/Super_combinator

dragonbonheur 8y ago

The other project named C-- http://c--sphinx.narod.ru/indexe.htm http://c--sphinx.narod.ru/indexe.htm

ginko 8y ago
At least that one actually defines a decrement operator.
vgoh1 8y ago
I used this in the mid- to late-90's on my 80386 (which was very much out of date at the time, but was all I had). I was very new to computing at the time, and the only other languages that I had under my belt were QuickBASIC and 80386 assembler, so I can't comment on if it were a "good" language or not. After less than a year, I ended up abandoning it, preferring to use QuickBASIC for high level, and machine language for low, not feeling like I needed the intermediate C--.

ThePadawan 8y ago

IIRC EiffelStudio compiled Eiffel to C-- as an intermediary stage, but I haven't used it since university and struggle to find information about that online.

_pmf_ 8y ago
Slightly off topic: did you do any projects using Eiffel, and if yes, what were the benefits / unique features?
- ThePadawan 8y ago
  I did not use it past university.

carterschonwald 8y ago

There’s an alternative timeline where c— was better marketed / promulgated as a backend tool kit for optimizing compilers and everyone use c— instead. That’s not to say llvm isn’t great, but some of the design choices it has make it a lot of work to do funky stuff ! And c— is a bit easier to write low level rts snippets in. I do think the ghc c— flavor is super nice to write in these days.

metalliqaz 8y ago

Sometime in the 90's I downloaded a programming language called "C--" that was basically assembly with some loop control structures and functions. I'm assuming this completely unrelated. Edit: ah, looks like dragonbonheur found and linked it already in this thread!

sprinx 8y ago
That was Sprinkx C-- Great Compiller with IDE in late 90's http://c--sphinx.narod.ru/indexe.htm http://c--sphinx.narod.ru/indexe.htm

gnulinux 8y ago

Does compiling to C-- have any benefits compared to compiling equivalent C code (maybe a subset of C)? My guess would be modern C compilers, powered by decades of R&D and programming, would be able to optimize just as well and possibly better. EDIT: One advantage that comes to my mind is that compiling to C-- will give slightly more power to deal with stack. E.g. implementing exceptions, continuations etc would be simpler. This is possible in C using inline assembly.

vmchale 8y ago
>My guess would be modern C compilers, powered by decades of R&D and programming, would be able to optimize just as well and possibly better. GHC often produces more efficient code than the LLVM backend.
ufo 8y ago
Another thing it helps with is garbage collection. If you compile down to C it also requires stack trickery.
rwhaling 8y ago
One benefit that is repeatedly mentioned in the papers is the ability to do tail-call optimization, which is more or less impossible with compile-to-c interpretations, and mandatory for functional languages.

vmchale 8y ago

Is GHC the only project that uses this?

ufo 8y ago

Are there any projects other than GHC which still use C--? I had heard that it was unfortunately kind of dead these days.

tempodox 8y ago

This looks like a precursor of LLVM IR.

inspector-g 8y ago

Interesting! I've been writing a lot of C/C++ for over a decade, but had never heard of C-- before. So, I went to the website[1] linked in the PDF to learn more, but sadly it appears the domain has been taken over and now just displays a small collection of badly written articles about Windows. [1] http://cminusminus.org http://cminusminus.org

DonHopkins 8y ago

Generalizing Overloading for C++2000: Bjarne Stroustrup, AT&T Labs, Florham Park, NJ, USA. Abstract: This paper outlines the proposal for generalizing the overloading rules for Standard C++ that is expected to become part of the next revision of the standard. The focus is on general ideas rather than technical details (which can be found in AT&T Labs Technical Report no. 42, April 1,1998). http://www.stroustrup.com/whitespace98.pdf http://www.stroustrup.com/whitespace98.pdf

DonHopkins 8y ago

C++++-= “C++++-= is the new language that is a little more than C++ and a lot less.” -Bill Joy In this talk from 1991, Bill Joy predicts a new hypothetical language that he calls “C++++-=”, which adds some things to C++, and takes away some other things. https://medium.com/@donhopkins/bill-joys-law-2-year-1984-million-instructions-per-second-3a8c92165cfe https://medium.com/@donhopkins/bill-joys-law-2-year-1984-mil...

evincarofautumn 8y ago

I would love to use it for my compiler backend…if I could find any maintained standalone implementations of it.