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1---
2navhome: /docs
3sort: 5
5---
7# Core, `|` ("bar")
9Core twigs are flow twigs. The compiler essentially pins a Nock
10formula, or battery of formulas, to the subject.
12All `|` twigs are macros around `$core`. (See the `$core`
13section in [`span`](../../basic#-core-p-span-q-map-term-span) above.)
14`$core` uses the subject as the payload of a battery, whose arms are
15compiled with the core itself as the subject.
17Four of these twigs (`:gate`, `:trap`, `:loop`, and `:gill`) produce a
18core with a single arm, named `$`. We can recompute this arm with changes,
19useful for recursion among other things:
21> `:moar()` expands to `:make($)`, accepting a *jogging* body
22> containing a list of changes to the subject.
24> `$()` expands to `%=($)`, accepting a *jogging* body
25> containing a list of changes to the subject.
28## Stems
30<list dataPreview="true" className="runes"></list>