How do I view the type of a scala expression in IntelliJ

Question

The Eclipse scala plugin has a nice feature which shows you the type of a variable when you hover the mouse over it. How do I see the same information with the IntelliJ plu

Answer 1

There's good tips gathered around here, but since the mappings vary by the keyboard bindings, here's a summary for the Mac OS X 10.5+ bindings.

• ctrl + hover: show the type of the expression

• alt + hover: clicking on the expression inspects its value (very handy!)

• ⌘ + hover works like ctrl+hover, but also allows clicking the link to go to other references of the expression (ctrl+click obviously doesn't because it is regarded as right click in OS X).

Note: The Mac OS X 10.5+ bindings are still not the default in IntelliJ 13.1, but they really should be. They have a more native OS X feel than the old Mac OS X bindings. You can activate them via Preferences > "keyboard" (in the search field) > Keymap > Keymaps: Mac OS X 10.5+

The real usability problem with these (as of IntelliJ 13.1) is that one needs to hold the key, then move the cursor. It should ideally also work when you have the cursor already on the expression, then start keeping ctrl/alt/cmd pressed in. I'll request them for this.

ps. I know it's OS X, officially, not Mac OS X. IntelliJ IDEA still uses the old naming at least for the keycaps.