A macro used to easily define user interface views in a declarative
manner.

(defview (NAME [:type TYPE] [:inherit-from INHERIT-FROM]
[:satisfies SATISFIES] VIEW-KWARGS...)
[FIELD-NAME
| (FIELD-NAME [:type FIELD-TYPE] [:initform INITFORM]
[:present-as PRESENT-AS] [:parse-as PARSE-AS]
FIELD-KWARGS...)]...)

In the above form, these metasyntactic variables have the following values:

NAME
When non-nil, an unevaluated unique symbol identifying the
view to other parts of the system that require a view,
resolving it using `find-view'.
TYPE
An unevaluated designator for the class of the resulting
view (determined by `view-class-name'), and half the
designator for the class of this view's fields (determined by
`view-field-class-name' applied to `view-default-field-type').
Defaults to `data'.
INHERIT-FROM
A designator for `view' slot `inherit-from'. Forms
like (:scaffold DATA-CLASS) will replace :scaffold with TYPE.
See `find-view' for further transformation.
SATISFIES
A designator for `form-view' slot `satisfies'.
VIEW-KWARGS
Other arguments passed directly to `make-instance' for the
resulting view, quoting subject to
`view-argument-quoting-strategy'.

INHERIT-FROM and SATISFIES are evaluated.

FIELD-NAME
An unevaluated designator for `view-field' slot `slot-name'.
FIELD-TYPE
A designator for the class of the field, in combination with
TYPE, as explained above for TYPE.
FIELD-KWARGS
Other arguments passed directly to `make-instance' for the
resulting view field, quoting subject to
`view-argument-quoting-strategy'.

However, FIELD-KWARGS keywords present in
`*custom-view-field-argument-compilers*' are not included in the
`make-instance' call; see that variable for how those are transformed.
The built-in custom view fields are as follows:

INITFORM
A form for `mixin-view-field' slot `initform' (which is
really an initfunction).
PRESENT-AS
A designator for `view-field' slot `presentation'. The symbol
or CAR is mapped to a class name through
`presentation-class-name', and the CDR, a series of keyword
arguments, is passed to `make-instance' on said class, subject
to `view-argument-quoting-strategy'.
PARSE-AS
A designator for `form-view-field' slot `parser'. Otherwise
similar to PRESENT-AS, but mapping class names using
`parser-class-name'.