@@ -33,11 +33,10 @@ AST:
3333
3434##### Semantics
3535
36−`|$` is used to declare a wet gate that is a mold builder. The mold builder
37−is polymorphic in its input types. `a` is a `lest` of `term` used as
38−identifiers for the input types. `b` is a structure built from elements of `a`.
39−The output of `|$` is a mold builder that produces a `spec` obtained by
40−substituting the input types parameterized by `a` into `b`.
36+`|$` is used to declare a wet gate mold builder that is polymorphic in its input molds. `a` is a `lest` of `term` used as
37+identifiers for the input molds. `b` is a structure built from elements of `a`.
38+The output of `|$` is a mold builder obtained by
39+substituting the input molds parameterized by `a` into `b`.
4140
4241##### Expands to
4342
@@ -54,10 +53,13 @@ body
5453
5554##### Discussion
5655
56+A mold builder is a wet gate from one or more molds to a mold. A mold is a
57+function from nouns to nouns with types that may be partial, is always
58+idempotent, and usually the identity function on the noun itself.
59+
5760`|$` is a restricted form of `|*`. The use of `|$` over `|*` is one of style, as either could
5861be used to make wet gates that are mold builders. The buc in `|$` is a hint that
59−`|$` is closely related to buc runes, and thus `|$` should be used to make wet
60−gates that produce mold builders, while `|*` should be used for any other sort of
62+`|$` is closely related to buc runes, and thus `|$` should be used to make mold builders, while `|*` should be used for any other sort of
6163wet gate. Thus, the second argument of `|$` is frequently a buc
6264rune. For further discussion of wet gates, see the entry for [`|*`](#bartar).
6365