4 ms·

> C was once supposed to be a simple language closer to a portable macro assembler than a high-level language, That might have been K&R's original intention, b

by jabl 6y ago

> C was once supposed to be a simple language closer to a portable macro assembler than a high-level language, That might have been K&R's original intention, but that went out the window pretty early on when optimizing compilers arrived on the scene. And eventually when the ANSI spec was written, it was explicitly written to allow all kinds of optimizations (the "as-if" rule).

gwd 6y ago
> And eventually when the ANSI spec was written, it was explicitly written to allow all kinds of optimizations (the "as-if" rule). The ironic thing about that is that when they wrote C89, they said they were trying to standardize existing practice. I don't think they had any idea that they were effectively declaring 90% of all programs buggy.
- jfkebwjsbx 6y ago
  And then retroactively declare that code broken and not conforming. Good times!
  - jabl 6y ago
    In defense of whoever was involved in the C89 process, I think they had an impossible task. At the same time they wanted to standardize the "portable macro-assembler" as well as allowing optimizations. With such constraints they could not but fail. With hindsight, maybe K&R should have consulted with PL experts and researchers and designed a "proper" language with a better emphasis on soundness and safety. I'm not saying they could have invented something like Rust back in the 1970'ies, but even then the state of the art was far ahead of K&R C.
- kps 6y ago
  > I don't think they had any idea that they were effectively declaring 90% of all programs buggy. I agree. During the standardization process, there was a proposal (‘noalias’) that dmr described as “a license for the compiler to undertake aggressive optimizations that are completely legal by the committee's rules, but make hash of apparently safe programs”, and, that “[i]t negates every brave promise X3J11 ever made about codifying existing practices, preserving the existing body of code, and keeping (dare I say it?) ‘the spirit of C.’”¹ If he or anyone else at the time had realized that ‘undefined behaviour’ would turn out to do the same, there response would have been the same: “[it] must go. This is non-negotiable.” ¹ https://www.lysator.liu.se/c/dmr-on-noalias.html https://www.lysator.liu.se/c/dmr-on-noalias.html

by jabl 6y ago

gwd 6y ago

> And eventually when the ANSI spec was written, it was explicitly written to allow all kinds of optimizations (the "as-if" rule). The ironic thing about that is that when they wrote C89, they said they were trying to standardize existing practice. I don't think they had any idea that they were effectively declaring 90% of all programs buggy.

jfkebwjsbx 6y ago
And then retroactively declare that code broken and not conforming. Good times!
- jabl 6y ago
  In defense of whoever was involved in the C89 process, I think they had an impossible task. At the same time they wanted to standardize the "portable macro-assembler" as well as allowing optimizations. With such constraints they could not but fail. With hindsight, maybe K&R should have consulted with PL experts and researchers and designed a "proper" language with a better emphasis on soundness and safety. I'm not saying they could have invented something like Rust back in the 1970'ies, but even then the state of the art was far ahead of K&R C.
kps 6y ago
> I don't think they had any idea that they were effectively declaring 90% of all programs buggy. I agree. During the standardization process, there was a proposal (‘noalias’) that dmr described as “a license for the compiler to undertake aggressive optimizations that are completely legal by the committee's rules, but make hash of apparently safe programs”, and, that “[i]t negates every brave promise X3J11 ever made about codifying existing practices, preserving the existing body of code, and keeping (dare I say it?) ‘the spirit of C.’”¹ If he or anyone else at the time had realized that ‘undefined behaviour’ would turn out to do the same, there response would have been the same: “[it] must go. This is non-negotiable.” ¹ https://www.lysator.liu.se/c/dmr-on-noalias.html https://www.lysator.liu.se/c/dmr-on-noalias.html