garnet/haskell/Main.hs

module Main (main) where

import Foreign.C.String (CString, withCString)

foreign import ccall safe "__c_hello" hello :: CString -> IO ()

main :: IO ()
main = withCString "Haskell" hello
Initial 2026-02-17 14:57:34 +00:00			`module Main (main) where`

Call Rust from Haskell with `cargo-cabal` and `hs-bindgen` See https://sraka.xyz/posts/hs-bindgen-introduction.html. For now, this is a shell-based workflow, rather than using Nix to build everything, i.e. `nix develop` works but `nix build` doesn't. And `cargo build` has to be called manually to create the C library, rather than `cabal` being clever enough to invoke it itself. We ran `cargo cabal init` from the `rust` directory (`nix shell github:yvan-sraka/cargo-cabal`), which generated `hsbindgen.toml` (which we use), and `Setup.lhs` (which just added `extra-lib-dirs`, and with the wrong paths, so we dspecify those statically instead in `garnet.cabal`). We also follow its advice to use `staticlib`. Also, after we ran the first `cargo build` (requiring a `mkdir rust/src` before it would run), we took the generated the Haskell file, and moved the main contents in to `Main.hs` manually. 2026-02-18 15:49:08 +00:00			`import Foreign.C.String (CString, withCString)`

			`foreign import ccall safe "__c_hello" hello :: CString -> IO ()`

Initial 2026-02-17 14:57:34 +00:00			`main :: IO ()`
Call Rust from Haskell with `cargo-cabal` and `hs-bindgen` See https://sraka.xyz/posts/hs-bindgen-introduction.html. For now, this is a shell-based workflow, rather than using Nix to build everything, i.e. `nix develop` works but `nix build` doesn't. And `cargo build` has to be called manually to create the C library, rather than `cabal` being clever enough to invoke it itself. We ran `cargo cabal init` from the `rust` directory (`nix shell github:yvan-sraka/cargo-cabal`), which generated `hsbindgen.toml` (which we use), and `Setup.lhs` (which just added `extra-lib-dirs`, and with the wrong paths, so we dspecify those statically instead in `garnet.cabal`). We also follow its advice to use `staticlib`. Also, after we ran the first `cargo build` (requiring a `mkdir rust/src` before it would run), we took the generated the Haskell file, and moved the main contents in to `Main.hs` manually. 2026-02-18 15:49:08 +00:00			`main = withCString "Haskell" hello`