Is it ever appropriate to hyphenate a verb phrase in French which is used like a single word?
In French, there are many verb phrases which are used like single words, and are not to be interpreted along with the grammar of the surrounding sentence, eg. ‘mise à jour’, ‘mise en jeu’, ‘garde à vue’, ‘coup de gueule’, etc. In English, one either tends to join these words together if they’re to be used like a noun, as German often does (eg. runaway, walkabout, notwithstanding, phonecall) or join them through hyphenation (eg. hold-up, hide-and-seek, down-to-earth). Is it ever appropriate to do this in French, or are these verb phrases always used as plain separate words?