doc/ref/curried.texi

   1 @c -*-texinfo-*-
   2 @c This is part of the GNU Guile Reference Manual.
   3 @c Copyright (C) 2012 Free Software Foundation, Inc.
   4 @c See the file guile.texi for copying conditions.
   5
   6 @node Curried Definitions
   7 @section Curried Definitions
   8
   9 The macros in this section are provided by
  10 @lisp
  11 (use-modules (ice-9 curried-definitions))
  12 @end lisp
  13 @noindent
  14 and replace those provided by default.
  15
  16 Prior to Guile 2.0, Guile provided a type of definition known colloquially
  17 as a ``curried definition''. The idea is to extend the syntax of
  18 @code{define} so that you can conveniently define procedures that return
  19 procedures, up to any desired depth.
  20
  21 For example,
  22 @example
  23 (define ((foo x) y)
  24   (list x y))
  25 @end example
  26 is a convenience form of
  27 @example
  28 (define foo
  29   (lambda (x)
  30     (lambda (y)
  31       (list x y))))
  32 @end example
  33
  34 @deffn {Scheme Syntax} define (@dots{} (name args @dots{}) @dots{}) body @dots{}
  35 @deffnx {Scheme Syntax} define* (@dots{} (name args @dots{}) @dots{}) body @dots{}
  36 @deffnx {Scheme Syntax} define-public (@dots{} (name args @dots{}) @dots{}) body @dots{}
  37
  38 Create a top level variable @var{name} bound to the procedure with
  39 parameter list @var{args}. If @var{name} is itself a formal parameter
  40 list, then a higher order procedure is created using that
  41 formal-parameter list, and returning a procedure that has parameter list
  42 @var{args}. This nesting may occur to arbitrary depth.
  43
  44 @code{define*} is similar but the formal parameter lists take additional
  45 options as described in @ref{lambda* and define*}. For example,
  46 @example
  47 (define* ((foo #:keys (bar 'baz) (quux 'zot)) frotz #:rest rest)
  48   (list bar quux frotz rest))
  49
  50 ((foo #:quux 'foo) 1 2 3 4 5)
  51 @result{} (baz foo 1 (2 3 4 5))
  52 @end example
  53
  54 @code{define-public} is similar to @code{define} but it also adds
  55 @var{name} to the list of exported bindings of the current module.
  56 @end deffn