Accidentally quadratic: When Python is faster than C++
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Re: Accidentally quadratic: When Python is faster than C++
#2I’ve been thinking about this lately. Can you actually be faster than C? Like, in the sense that you can transpile any bit of Python or Lisp or Haskell or Rust or JS into C but the opposite isn’t necessarily true because not all those language support all the features exposed in C (such as goto, no bounds checking, pointer arithmetic, etc.), any algorithm for say parsing JSON can be expressed equally as efficiently in C, while a clever and hacky C-specific algorithm cannot necessarily be expressed in those higher level languages.
In other words, is “faster than C” even a good metric if all it means that “if you implement something inefficiently in C it will be faster than if it is implemented efficiently in not-C”?
Re: Accidentally quadratic: When Python is faster than C++
#3I’ve been thinking about this lately. Can you actually be faster than C? Like, in the sense that you can transpile any bit of Python or Lisp or Haskell or Rust or JS into C but the opposite isn’t necessarily true because not all those language support all the features exposed in C (such as goto, no bounds checking, pointer arithmetic, etc.), any algorithm for say parsing JSON can be expressed equally as efficiently i…
Rust already does better than C for some benchmarks. See: https://benchmarksgame-team.pages.debian.net/benchmarksgame/...
Re: Accidentally quadratic: When Python is faster than C++
#4I’ve been thinking about this lately. Can you actually be faster than C? Like, in the sense that you can transpile any bit of Python or Lisp or Haskell or Rust or JS into C but the opposite isn’t necessarily true because not all those language support all the features exposed in C (such as goto, no bounds checking, pointer arithmetic, etc.), any algorithm for say parsing JSON can be expressed equally as efficiently i…
Sure, managed languages can beat C performance. IIRC, the JVM can reorder branches on the fly to avoid jumps.
Re: Accidentally quadratic: When Python is faster than C++
#5I’ve been thinking about this lately. Can you actually be faster than C? Like, in the sense that you can transpile any bit of Python or Lisp or Haskell or Rust or JS into C but the opposite isn’t necessarily true because not all those language support all the features exposed in C (such as goto, no bounds checking, pointer arithmetic, etc.), any algorithm for say parsing JSON can be expressed equally as efficiently i…
I think about programming languages like I do cars. While rust may be a Ferrari, some kid who doesn't know how to drive a stick and has only had his license for about a month is going to have a rough time beating you driving from New York to Texas even if you're driving a Corolla. I consider myself to be an extremely good software engineer, but lower level programming languages scare me. Recently I've been riding a lot of code in C++ for my Arduino project, but aside from that I can't stand it. You have to be such a good C programmer to make things faster than you probably could knock out using Python + numpy or something like that, but to be fair under the hood numpy uses tons of optimized C code.
Re: Accidentally quadratic: When Python is faster than C++
#6I’ve been thinking about this lately. Can you actually be faster than C? Like, in the sense that you can transpile any bit of Python or Lisp or Haskell or Rust or JS into C but the opposite isn’t necessarily true because not all those language support all the features exposed in C (such as goto, no bounds checking, pointer arithmetic, etc.), any algorithm for say parsing JSON can be expressed equally as efficiently i…
If you use the normal toolchains for C vs another language, the other language still can be faster because it can dynamically generate bytecode based on runtime information. In the normal C toolchain, this is not possible.
However, if you used an alterative toolchain that could also generate bytecode from C at runtime, then I would bet that C would stay on top or be equal.
Re: Accidentally quadratic: When Python is faster than C++
#7I’ve been thinking about this lately. Can you actually be faster than C? Like, in the sense that you can transpile any bit of Python or Lisp or Haskell or Rust or JS into C but the opposite isn’t necessarily true because not all those language support all the features exposed in C (such as goto, no bounds checking, pointer arithmetic, etc.), any algorithm for say parsing JSON can be expressed equally as efficiently i…
C loses some optimization potential because of aliasing; it can't be guaranteed that some pointer operation isn't going to change a variable anywhere in memory so that limits certain reordering and loop optimizations.
Languages without arbitrary pointers don't have this issue and safely assume they knows all the assignments done to values in memory allowing for optimizations.
Re: Accidentally quadratic: When Python is faster than C++
#8Have academic CS articles always had click-bait titles?
Re: Accidentally quadratic: When Python is faster than C++
#9I’ve been thinking about this lately. Can you actually be faster than C? Like, in the sense that you can transpile any bit of Python or Lisp or Haskell or Rust or JS into C but the opposite isn’t necessarily true because not all those language support all the features exposed in C (such as goto, no bounds checking, pointer arithmetic, etc.), any algorithm for say parsing JSON can be expressed equally as efficiently i…
Be careful when you say that everything can be converted to C. While that's true in a naive fashion, it gets rid of a lot of additional information.
For example, Rust can sometimes beat C because it's (1) often more friendly to auto-vectorization and (2) it has additional aliasing information.
Re: Accidentally quadratic: When Python is faster than C++
#10I’ve been thinking about this lately. Can you actually be faster than C? Like, in the sense that you can transpile any bit of Python or Lisp or Haskell or Rust or JS into C but the opposite isn’t necessarily true because not all those language support all the features exposed in C (such as goto, no bounds checking, pointer arithmetic, etc.), any algorithm for say parsing JSON can be expressed equally as efficiently i…
Sure, theoretically.
For instance, C function calls always do some things (like preserving the stack) that may not always be necessary.
I sure wouldn't want to to TRY to beat a C compiler, but it seems obvious to me that it is possible.