Another great concept is that function application and array indexing has the same syntax. a.map(f) is basically† just: f[a] and: a.map(x => m[

Another great concept is that function application and array indexing has the same syntax. a.map(f) is basically† just: f[a] and: a.map(x => m[x]) is still just: m[a] †: Rank notwithstanding. If that bothers you that f might take an atom, pretend I said f@/:a and m@/:a instead.