Haskell and low-level actions

Question

How do low-level things like sockets, pipes, and I / O files get implemented in Haskell? I assume these I / O methods are not native in Haskell, but Haskell is quickly wrapping some low-level C library, is this correct?

Answer 1

Sockets, pipes, and files are implemented in the kernel; To use them from a user space program, you need to call the kernel. If you consider the kernel as a library, then yes, I / O is necessarily implemented by a low-level C / assembler library.

In practice, Haskell implementations such as GHC will use C library wrappers around system calls. See the GHC RTS comment for a description of the C bits that make up the core of any Haskell program compiled with GHC. If in doubt, refer to the source code .

Answer 2

"fast wrap" is not always the best description here.

• This sometimes ends in the sense that you are wrapping a package (e.g. wxcore wraps wx).
  This is closest to the “fast packaging” you mentioned, but I think it's best to call it thin packaging, because I don't think it's as simple as all of this.
• Sometimes it wraps around like upholstery, wraps around a chair (e.g. wxHaskell wraps wx).
  I would call it "built."
• Sometimes it wraps around like a car, wraps around an engine (for example, wx reactive banana wraps).
  I would call it "use", and if you look at it, you will see the engine there, but it does not look like the engine, and you use it in a completely different way.
• Sometimes it is wrapped, like trucks, wraps a freight train (for example, haskell threads carry OS threads). I would call it "overridden." (Haskell can use OS threads, but native Haskell threads are much lighter.)

You can argue that since the GHC runtime system is written in C, and your OS was probably written in C, Haskell is a wrapper around C, but it is, as you say, a Spyker C8 machine that wraps the Audi V8 engine. Spyker can be upset if you call your beautiful C8 box with Audi in it. When you drive a car, you use the engine, but not directly. Some people like to tune their car, as some people like to overclock their processor, but you don't need it if you don't want to. Some people say that you need to know how the engine works if you want to understand your car.

If you can forgive the Formula 1 links, basically Haskell wraps C like Torro Rosso wraps Ferrari, but sometimes it looks like Maclaren wraps Mercedes. (Before you call Torro Rosso slowly, compare it with a Ford.)