=> sets the subject to its head, then evaluates its tail against it.

=>([a=1 b=2] b) is 2.

|% makes a core: a battery of named arms, each written ++ name.

reach an arm back out with =< or arm:core.

=<  a
|%
++  a  5
--

is 5.

^: turns a type into a factory gate that molds any noun to that type.

(^:(@ud) 5) is 5.

list is the type of a null-terminated sequence.

(list @) is a list of atoms; the empty list is ~.

%: 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)

lent is how many elements a list has.

(lent `(list @)`~[8 9 10]) is 3.

^- casts a value to a named type: it checks the value fits and relabels it.

^-(@ 42) is 42.

irregular forms:

a leading backtick cast - the type in backticks, then the value - is ^-

:~ makes a null-terminated list.

:~(1 2 3) is ~[1 2 3].

irregular forms:

~[a b c] is :~(a b c)