|^ bar·ket

|^ hoon ++ term hoon ... ++ term hoon --|^ syntax is a combination of the |= rune and the |% rune:
  • The first child is some hoon expression which defines the core’s $ arm, which is computed immediately, just as in a |= gate.
  • The remaining expressions must be pairs of a term and some hoon, marked by ++ or another arm marker, just as in the |% core
  • |^ must be closed by the boundary --, just as in the |% core
The $ arm is evaluated immediately after creation of the core.

Produce a core whose battery includes an arm named buc, which is evaluated immediately, and at least one additional arm (named something else).

Documentation on urbit.org