Most unix command line commands, when presenting a long list of results in columns, choose to sort them in columns so that you read through the list alphabetically from top left down the first column, then down the next to the right and so on.

The Scala REPL displays lists of command completions (when TAB is pressed) ordered in rows: starting top left, reading to the right and then on to the next row left to right.

Whilst the current Scala behaviour is consistent with reading of normal English text, it is not consistent with reading of text presented in columns and makes scanning through for correct values harder. It is also inconsistent within a Unix command line environment.