Prepare a environment for practice

Install haskell-stack

Install stack: curl -sSL https://get.haskellstack.org/ | sh (ref)

Import it in IntelliJ

1. Download and install the latest beta version of plugin IntelliJ-Haskell. You can do so by adding https://plugins.jetbrains.com/plugins/alpha/8258 to you IntelliJ's customer plugin repository list.
2. Menu "File" -> "New" -> "Import Project from Existing Source".
3. First time you run it takes a long time to fetch all dependencies.
4. If plugin doesn't work properly enable "Haskell Log" in your "Event Log" window.

In case you need to create a fresh project

1. Create sample project from simple template using stack new demo01 simple
2. Go in project root. Fetch dependencies and appropriate GHC using stack setup Build executable output using stack build
3. Aside from simple template you can use stack-templates.