Wings

[%wing p=(list limb)]

A wing is a limb search path into the subject.

Produces

A wing is a list of limbs (including a trivial list of one limb). The limbs are resolved in succession. The result of the last limb resolution is the value produced by the wing expression.

Syntax

Irregular: a.b.c. Read this as 'a in b in c'. Finds limb a within limb b within limb c of the subject.

Discussion

Intuitively, Hoon wings are written in the opposite order from attribute dot-paths in most languages. Hoon a.b.c is Java's c.b.a; it means "a within b within c."

Any item in the wing can resolve to a leg (fragment) or arm (computation). But if a non-terminal item in the wing would resolve to an arm, it resolves instead to the subject of the arm -- in other words, the core exporting that name.

The mysterious idiom ..b produces the leg b if b is a leg; the core exporting b if b is an arm. Since . is the same limb as +, ..b is the same wing as +1.foo.

Examples

~zod:dojo> =a [fod=3 bat=[baz=1 moo=2]]

~zod:dojo> bat.a
[baz=1 moo=2]

~zod:dojo> moo.bat.a
2

Wing Resolution

There are two common syntaxes used to resolve a wing path into the current subject: . dot and : col.

• . dot syntax, as c.b.a, resolves the wing path into the subject at the right hand using Nock 0 (or possibly Nock 9 or Nock 10 depending on the expression).

  > !,(*hoon c.b.a)
  [%wing p=~[%c %b %a]]
  

• The : col operator expands to a => tisgar to resolve the wing path against its right-hand side as the subject. This can be a Nock 7 or possibly optimized by the compiler to a Nock 0.

  > !,(*hoon c:b:a)
  [%tsgl p=[%wing p=~[%c]] q=[%tsgl p=[%wing p=~[%b]] q=[%wing p=~[%a]]]]