[geocar]

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.