I’m trying to set up some custom mix tasks for working with elm but when I call:

Mix.shell.cmd("elm init")

I get the prompt from elm asking whether to proceed in creating elm.json, but after I type ‘y’ and hit enter the process hangs.

When I break out, the message

thread blocked indefinitely in an MVar operation

is printed to the console. I searched for this string, and only get back results relating to Haskell so I’m guessing the elm compiler and mix/elixir aren’t playing nice together when user input is required.

The following command works fine (presumably because it doesn’t require any user input from the cmd line):

Mix.shell.cmd("elm make #{@elm_src}  --output=#{@elm_output_file} --debug")

I’ve also tried with System.cmd to no avail.

Any ideas on how to interact with Elm/Haskell from a mix task? Is it even possible?

Thanks