APL is best thought of, not as a "programming language", but as a DSL for array manipulation. The syntax is sadly dead. The semantics live on in the most mainstream of places, notably Numpy.

Trying to write entire full-features programs in APL should be thought of as roughly the same as doing so in Awk. Possible, and even beautiful - but not a serious endeavor. We'd be better off if other languages incorporated APL as a first class DSL, the same way they incorporated regex.