@@ -14,6 +14,17 @@ section in [`span`](../../basic#-core-p-span-q-map-term-span) above.)
1414`$core` uses the subject as the payload of a battery, whose arms are
1515compiled with the core itself as the subject.
1616
17+Four of these twigs (`:gate`, `:trap`, `:loop`, and `:gill`) produce a
18+core with a single arm, named `$`. We can recompute this arm with changes,
19+useful for recursion among other things:
20+
21+> `:moar()` expands to `:make($)`, accepting a *jogging* body
22+> containing a list of changes to the subject.
23+
24+> `$()` expands to `%=($)`, accepting a *jogging* body
25+> containing a list of changes to the subject.
26+
27+
1728## Stems
1829
1930<list dataPreview="true" className="runes"></list>