=/ pins a named value (a face) into the subject for the lines below it.

name=value optionally declares the type.

=/(a 3 (add a a)) is 6.

=. changes one face in the subject, leaving the rest, for the lines below.

=/(a [p=1 q=2] =.(p.a 9 a)) is [p=9 q=2].

%: calls a gate with several arguments, gathering them into one sample.

%:(add 2 3) is 5.

irregular forms:

(gate a b c) is %:(gate a b c)

add sums two atoms.

(add 2 3) is 5.