3 ms·

Many languages — Haskell included — can compile to C. Compiling down to C and then piggybacking off the system C compiler is a fairly common way of getting a so

by chc 14y ago

Many languages — Haskell included — can compile to C. Compiling down to C and then piggybacking off the system C compiler is a fairly common way of getting a sophisticated native codegen without needing to implement one yourself. But simply compiling down to C doesn't necessarily put the language in the same relationship with C that CoffeeScript is with JavaScript. To be honest, I could imagine a slightly nicer skin over C, but C is already a pretty good C. Any "CoffeeScript for C" would probably work out to a poor reimplementation of an early C++ compiler with the semicolons removed.

tikhonj 14y ago
This isn't compiling Haskell down to C. It's using a DSL to generate C. The DSL just happens to be embedded in Haskell. Haskell is just an environment, a language factory. Haskell is used for creating the abstractions and meta-programming. You can also piggy back on Haskell's type system to enforce certain invariants. But ultimately the semantics of the DSL--what actually gets turned into C--are not necessarily related to Haskell at all. Instead, the semantics are tailored for your particular application. In the particular case of atom, this application is hard real-time programming. Another example is something one of my friends worked on in OCaml. He essentially created a little algebraic system which provided all the operations for a field (with maybe a couple other ones). This is enough to implement a bunch of variations on a Kalman filter. He could then iterate quickly and test the code locally; when he was content, he could use the same code to output abstraction-free C which he could then compile and deploy on ARM. The point being that the host language is not related to C; it's the embedded DSL that plays the role of CoffeeScript. (Although any reasonable DSL would be quite a larger departure from C than CoffeeScript is from JavaScript.) You just use Haskell/OCaml/Scala/whatever to save having to implement a parser, type system and so on.
steveklabnik 14y ago
I thought `-f-via-c` was removed long ago.
- chc 14y ago
  AFAIK it isn't removed, but it is no longer developed and requires GHC to be in unregistered mode, which most people's won't be. But I could simply be behind the times.
  - steveklabnik 14y ago
    Looking into it, we're both right, in a way: > This is the oldest code generator in GHC and is generally not included any > more having been deprecated around GHC 7.0. Select it with the -fvia-C flag. So it was deprecated, just never removed.

by chc 14y ago

tikhonj 14y ago

This isn't compiling Haskell down to C. It's using a DSL to generate C. The DSL just happens to be embedded in Haskell. Haskell is just an environment, a language factory. Haskell is used for creating the abstractions and meta-programming. You can also piggy back on Haskell's type system to enforce certain invariants. But ultimately the semantics of the DSL--what actually gets turned into C--are not necessarily related to Haskell at all. Instead, the semantics are tailored for your particular application. In the particular case of atom, this application is hard real-time programming. Another example is something one of my friends worked on in OCaml. He essentially created a little algebraic system which provided all the operations for a field (with maybe a couple other ones). This is enough to implement a bunch of variations on a Kalman filter. He could then iterate quickly and test the code locally; when he was content, he could use the same code to output abstraction-free C which he could then compile and deploy on ARM. The point being that the host language is not related to C; it's the embedded DSL that plays the role of CoffeeScript. (Although any reasonable DSL would be quite a larger departure from C than CoffeeScript is from JavaScript.) You just use Haskell/OCaml/Scala/whatever to save having to implement a parser, type system and so on.

steveklabnik 14y ago

I thought `-f-via-c` was removed long ago.

chc 14y ago
AFAIK it isn't removed, but it is no longer developed and requires GHC to be in unregistered mode, which most people's won't be. But I could simply be behind the times.
- steveklabnik 14y ago
  Looking into it, we're both right, in a way: > This is the oldest code generator in GHC and is generally not included any > more having been deprecated around GHC 7.0. Select it with the -fvia-C flag. So it was deprecated, just never removed.