Download link for the Blang IDE is available here.
The only requirement is that Java 11 SDK should be installed on the system.
Really, "installing" amounts to unzipping and copying the contents. The folder contains both the IDE, a template for your own projects, and some command line tools.
The first time you try to launch BlangIDE, depending on the version of Mac OS X and/or security settings, you may get a message saying the "app is not registered with Apple by an identified developer". To work around this, follow these instructions (from Apple) the first time you open the BlangIDE (then Mac OS will remember your decision for subsequent launches):
In the Finder, locate BlangIDE (don't use Launchpad to do this).
Control-click the app icon, then choose Open from the shortcut menu.
If this does not work, an alternative is also described in the same Apple help page.
Blang projects have some dependencies. Here's a robust way to get them:
From the terminal, cd into [downloaded blang folder]/workspace/blangExample
./gradlew assemble eclipse. This will download the dependencies.
Now import in Blang IDE:
When asked which workspace to use, pick [downloaded blang folder]/workspace.
Select menu File > Import > General > Existing project into Workspace
Select [downloaded Blang folder]/workspace/blangExample
The blang project is ready. In the left tool bar, the project is in the
file explorer. Right click on blangExample/src/main/java/demo/ and
select the contextual menu New > File.
Name the file MyModel.bl. The extension choice must always be .bl
Select menu Run > Run Configuration..
Click on Java Application
Click on the New Launch Configuration on the top left.
Fill the Main class using the Search button.
In the tab Arguments add any required arguments.