How useful would learning APL be for writing less strictly array-based languages like Matlab?

Given you could even use it commercially (it requires an enterprise license, but I suppose Matlab does too), moderately useful conceptually, weakly useful mechanically. APL is very limited in what offers you. I did a ML course in Matlab a while ago and I remember I could scalar loops and procedural scripts, had nice tables and object-ike structures. You'd give that all up in APL so it wouldn't help you there, but you'd see how far you can get only with creative 'array language semantics'.

	▲	lokedhs 6 hours ago \| parent [-]
		Dyalog APL, along with other modern array languages that are related to it can all do imperative programming with loops etc. There are certainly valid arguments that you hive certain things up when moving to an array language, but loops are not one of those. That said, you won't use loops as much, but that's not because loops are not available.