A very simple Alpaca example application providing two HTTP endpoints with elli.
In preparing for the Alpaca v0.2.8 release this has turned up a number of basic usability issues for Alpaca:
- no source annotations in the code generator output makes for a quite frustrating development and debugging experience as this means no stack traces! This will be pretty much top of my list for v0.2.9 and I might even delay v0.2.8 for it.
- exhaustiveness checks when using pattern matching in function heads can fail when the checker tries to load a type from a module that has already been compiled. E.g. if
elli_request.alp
has already been built successfully, exhaustiveness checks ofendpoint.alp
will throw errors because the module forelli_request.alp
doesn't appear to be available. - incorrect line numbers in some type errors.
- some frustrating issues around multi-arity functions and type specifications for them e.g. there appear to be problems when
handle/1
andhandle/2
both exist but only a spec forhandle/1
is available. I haven't dug into this too deeply yet so it may be more complicated or even rather simple.
This currently uses some pending changes to the rebar3 plugin from lepoetemaudit that allow a pre-built version of Alpaca to be used directly.
You will need a local build of Alpaca, basic steps:
- clone the language repository
- build a local untagged Alpaca distribution
- set the
ALPACA_ROOT
environment variable to the location of your local Alpaca build
Here are the basic steps:
$ git clone https://github.com/alpaca-lang/alpaca.git
$ cd alpaca
$ rebar3 compile
$ bash ./make-release.sh
$ export ALPACA_ROOT=`pwd`/alpaca-unversioned_
Then you should be able to build and run this elli example:
$ cd $WHEREVER_YOU_CLONED_THIS_REPO
$ rebar3 clean
$ rebar3 release
$ ./_build/default/rel/alpaca_elli_example/bin/alpaca_elli_example foreground
Then:
➜ alpaca_elli_example git:(master) ✗ curl localhost:3000/test
Test endpoint.
➜ alpaca_elli_example git:(master) ✗ curl localhost:3000/hello/world
Hello, world
➜ alpaca_elli_example git:(master) ✗ curl localhost:3000/hello/Wat
Hello, Wat
➜ alpaca_elli_example git:(master) ✗ curl -X PUT localhost:3000/hello/Wat
Not found
➜ alpaca_elli_example git:(master) ✗