A Haskell to WebAssembly compiler. Project status: alpha, in active development, some simple examples already work.
See the documentation for further instructions. Or check our blog posts:
- Fibonacci compiles end-to-end: Haskell to WebAssembly via GHC
- Haskell WebAssembly calling JavaScript and back again
- Asterius GHC WebAssembly backend reaches TodoMVC
Also, we've added Weekly Status Reports in case you're interested where the bleeding edge has reached.
We provide pre-built Docker images. Put the input .hs program in a directory and map the directory to a Docker volume:
terrorjack@ubuntu:~$ docker run -it -v ~/mirror:/mirror terrorjack/asterius
root@76bcb511663d:~# cd /mirror
root@76bcb511663d:/mirror# ahc-link --input-hs xxx.hs
...
See the help text of ahc-link for further instructions.
What works currently:
- All GHC language features except Template Haskell.
- Non-IO parts in
ghc-prim/integer-simple/base/array/deepseq/containers/transformers/mtl/pretty/bytestring/binary/xhtml. IO is achieved via rts primitives likeprint_i64or JavaScript FFI. - Fast arbitrary-precision
Integeroperations backed byBigInts. - Preliminary copying GC, managing both Haskell heap objects and JavaScript references.
- Preliminary Cabal support.
- Importing JavaScript expressions via the
foreign import javascriptsyntax. First-classJSValtype in Haskell land. - Fast conversion between Haskell/JavaScript types (strings, arrays and ArrayBuffers at the moment)
- Calling Haskell functions from JavaScript via the
foreign export javascriptsyntax. Haskell closures can be passed between Haskell/JavaScript boundary viaStablePtr. - Invoking RTS API on the JavaScript side to manipulate Haskell closures and trigger evaluation.
- A linker which performs aggressive dead-code elimination, producing as small WebAssembly binary as possible.
- A debugger which checks invalid memory access and outputs memory loads/stores and control flow transfers.
- Complete
binaryen/wabtraw bindings, plus a monadic EDSL to construct WebAssembly code directly in Haskell. - A Haskell library to handle WebAssembly code, which already powers binary code generation.
- Unit tests implementing stochastic fuzzer/shrinker for WebAssembly, in order to produce minimal repro in case something goes wrong in generated code.
- Besides WebAssembly MVP and
BigInt, no special requirements on the underlying JavaScript engine at the moment. Optionally, we emit binaries using the experimental tail call opcodes; see theahc-linkdocumentation page for details.
Better check the fib, jsffi, array, rtsapi and teletype test suites first to get some idea on current capabilities of asterius.
install the following:
nodejs12.x. Binaries can be downloaded fromnoderesource/distributionsfor common*nixplatforms.
and then follow the commands in the Dockerfile.
For hacking instructions, there is a docs/hacking.md which has advice and common commands
Asterius is maintained by Tweag I/O.
Have questions? Need help? Tweet at @tweagio.