!!
(snoc `(list @)`~[1 2] 4)

snoc appends one element at the end.

glossary

%: 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)

snoc appends one element to the end of a list.

(snoc `(list @)`~[1 2] 4) is ~[1 2 4].

^- 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 ^-

list is the type of a null-terminated sequence.

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

:~ makes a null-terminated list.

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

irregular forms:

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