a json value is not yet a hoon value. dejs:format holds gates that convert one, and crash on the wrong shape.
ni converts a json number to a @ud. produce input as a number.
=> 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.
%= resolves a wing with some faces changed.
=/(a [x=1 y=2] a(x 9)) is [x=9 y=2].
irregular forms:
a(x 9) is %=(a x 9)
$(a b) restarts a loop with a changed to b