Wasm support

[dhess]

Hi! We're looking for a Selda replacement, and Beam looks promising.

We'd like to use beam-sqlite with GHC's Wasm backend, but it currently fails to build due to missing getProcessID support (or equivalent):

beam/beam-sqlite/Database/Beam/Sqlite/Connection.hs

Line 393 in df0080e

processId <- fromString . show <$> getProcessID

It appears Beam uses the process ID only as a unique identifier for the purposes of tracking a particular savepoint in runInsertReturningList. Could getProcessID potentially be replaced in Wasm by a pseudo-random number, instead?

[LaurentRDC]

I'm not opposed in principle. It would be cool to make beam compatible with the wasm GHC backend.

I'm not familiar with the beam-sqlite backend, but I'll try to take a look over the next few days

[LaurentRDC]

As pointed out, there's no requirement on using process IDs. Using a random positive integer based on the timestamp is sufficient.

@dhess I haven't built any Haskell packages using the wasm backend; how can I test that beam-core and beam-sqlite compile correctly?

[dhess]

@LaurentRDC We use this project, and it works well:

• https://gitlab.haskell.org/haskell-wasm/ghc-wasm-meta

It works as a Nix flake, if you're familiar with Nix, or you can run a Nix-less setup that puts everything in ~/.ghc-wasm. I believe that even GHCup points its users to this repo.