Compiling takes place in the background, when a source file is saved. Compiler errors and warnings are displayed in the Problems view. You can, however, also view the complete compiler output of the build.

You have to turn this on in the Preferences: menu Window > Preferences, then select Functional Programming > Haskell > Compiler and check the Show compiler output in view checkbox.

The Compiler output view is located on the bottom right of the workbench.

In the Preferences for the New Project wizard you can edit the default values for these properties (Window > Preferences > Functional Programming > Haskell > New Project). You can also let the project folder the combined source/binary/output folder.