Multi-package Reflex example
This repo is an example of combining
jsaddle to drastically improve the
Either clone this repo with
--recurse-submodules, or run
git submodule update --init --recursive in this directory after cloning
to make sure
reflex-platform is checked out.
./reflex-platform/try-reflex at least once. We won't use
it at all in this project, but it does some extra work to setup your
system requirements automatically, namely installing Nix and
configuring the Reflex binary cache.
Once Nix is installed, everything else is mostly handled for you. To
build the project's backend and
jsaddle-webkit2gtk frontend app, use
$ ./cabal new-build all
To build the GHCJS app, use the
$ ./cabal-ghcjs new-build all
You can use GHCi with the
jsaddle-webkit2gtk app for much better dev
$ ./cabal new-repl frontend
Nix is useful for creating deterministic, production ready build
products. You can use the
nix-build command to build all the parts
of the project with Nix.
$ nix-build trace: Skipping ios apps; system is x86_64-linux, but x86_64-darwin is needed. Use `nix-build -A all` to build with remote machines. See: https://nixos.org/nixos/manual/options.html#opt-nix.buildMachines /nix/store/5p041yq3ldniji7xizrxihmhmr576vah-reflex-project $ tree result result ├── android │ └── frontend -> /nix/store/4w62ly3hi75zpdmiq52lk1m4kir660vc-android-app ├── ghc │ ├── backend -> /nix/store/bgraikacjv68lfcghkprj3mspwx9f2bn-backend-0.1.0.0 │ ├── common -> /nix/store/lcgz36j77y6w7jyd39b14zp00hfaxn3s-common-0.1.0.0 │ └── frontend -> /nix/store/h9dbc2dvh11g1saj52ndn8ys3kj6f03l-frontend-0.1.0.0 └── ghcjs ├── common -> /nix/store/fgbmn6mjgh7gfdbgnb7a21fsb9175gmv-common-0.1.0.0 └── frontend -> /nix/store/hfpq2580jbvgm20p992v8qjdczvr20gm-frontend-0.1.0.0 9 directories, 0 files
Build the backend
$ nix-build -o backend-result -A ghc.backend
Build the JS app
$ nix-build -o frontend-result -A ghcjs.frontend
Build the native frontend
$ nix-build -o native-frontend-result -A ghc.frontend
Building a multi-package project with Nix can be a pain because of
Nix's lack of incremental building. A small change to a common package
will require Nix to rebuild that package from scratch, causing a huge
interruption during development. Although this is usually where Stack
would shine, Stack doesn't officially support using Nix for Haskell
derivations, and has zero support for Nix with GHCJS. You can build
Reflex apps using only Stack and no Nix, but you lose a lot of
reflex-platform provides, like the curated set of
package versions that Reflex works best with (including a
textlibrary), binary caches of all the Haskell
derivations, and zero-effort cross compilation for native mobile apps.
How it works
- Actually implement a backend / frontend that uses the
commonlibrary to show that even cross-package dependencies are built incrementally.
new-builddoesn't yet support any means of programmatically finding build products. It would be nice to have some kind of solution for this, especially so that the backend could serve the
dist-ghcjsproducts without some hardcoded path.