@node Lenses
@section Lenses

Provided by the module @code{(hnh util lens)}

@c TODO write an actuall introduction here

@defun modify object lens f args ...
@end defun

@defmac modify* object lens
@defmacx modify* object lens rest ...
@end defmac

@defmac set object lenses ... value
@end defmac

@defmac get object lenses ...
@end defmac


@defun make-lens getter setter
@end defun

@defmac build-lens getter setter
Where any of getter or setter can either be a single symbol, or a list.
@end defmac

@deftp {Scheme Lens} identity-lens
@end deftp

@defun compose-lenses lenses ...
@defunx lens-compose lenses ...
Lenses composes left to right, so earlier lenses in @var{lenses} are
applied earlier.
@end defun

@deftp {Scheme Lens} ref idx
Focuses the element at index @var{idx} in a list.
@end deftp

@deftp {Scheme Lens} car*
@deftpx {Scheme Lens} cdr*
Focuses the first or second element of a pair.
@end deftp

@defun each object lens proc
@end defun