guile/doc/ref/curried.texi

@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
@c Copyright (C) 2012 Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.

@node Curried Definitions
@section Curried Definitions

The macros in this section are provided by
@lisp
(use-modules (ice-9 curried-definitions))
@end lisp
@noindent
and replace those provided by default.

Prior to Guile 2.0, Guile provided a type of definition known colloquially
as a ``curried definition''. The idea is to extend the syntax of
@code{define} so that you can conveniently define procedures that return
procedures, up to any desired depth.

For example,
@example
(define ((foo x) y)
  (list x y))
@end example
is a convenience form of
@example
(define foo
  (lambda (x)
    (lambda (y)
      (list x y))))
@end example

@deffn {Scheme Syntax} define (@dots{} (name args @dots{}) @dots{}) body @dots{}
@deffnx {Scheme Syntax} define* (@dots{} (name args @dots{}) @dots{}) body @dots{}
@deffnx {Scheme Syntax} define-public (@dots{} (name args @dots{}) @dots{}) body @dots{}

Create a top level variable @var{name} bound to the procedure with
parameter list @var{args}. If @var{name} is itself a formal parameter
list, then a higher order procedure is created using that
formal-parameter list, and returning a procedure that has parameter list
@var{args}. This nesting may occur to arbitrary depth.

@code{define*} is similar but the formal parameter lists take additional
options as described in @ref{lambda* and define*}. For example,
@example
(define* ((foo #:keys (bar 'baz) (quux 'zot)) frotz #:rest rest)
  (list bar quux frotz rest))

((foo #:quux 'foo) 1 2 3 4 5)
@result{} (baz foo 1 (2 3 4 5))
@end example

@code{define-public} is similar to @code{define} but it also adds
@var{name} to the list of exported bindings of the current module.
@end deffn