> For the complete documentation index, see [llms.txt](https://docs.urbit.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.urbit.org/hoon/limbs/wing.md).
# Wings
Reference for wings in Hoon, which are lists of limbs forming search paths into the subject to access nested data and computations.
`[%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
> !,(*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
> !,(*hoon c:b:a)
[%tsgl p=[%wing p=~[%c]] q=[%tsgl p=[%wing p=~[%b]] q=[%wing p=~[%a]]]]
```
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