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Make imalison:compose return an anonymous function

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Also provide a unary version of imalison:compose
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Ivan Malison 2016-06-21 14:44:08 -07:00
parent b981768c8f
commit ec06e57d21
1 changed files with 16 additions and 2 deletions
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dotfiles/emacs.d/README.org
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@ -429,9 +429,9 @@ The composed functions can take arbitrarily many arguments and returning arbitra
thing
(list thing)))
(defmacro imalison:compose (name &rest funcs)
(defmacro imalison:compose (&rest funcs)
"Build a new function with NAME that is the composition of FUNCS."
`(defun ,name (&rest args)
`(lambda (&rest args)
(imalison:compose-helper ,funcs)))
(defmacro imalison:compose-helper (funcs)
@ -441,6 +441,20 @@ The composed functions can take arbitrarily many arguments and returning arbitra
`(apply ,(car funcs)
(imalison:make-list (imalison:compose-helper ,(cdr funcs))))))
#+END_SRC
Here is a unary version which avoids all the calls to imalison:make-list
#+BEGIN_SRC emacs-lisp
(defmacro imalison:compose-unary (&rest funcs)
"Build a new function with NAME that is the composition of FUNCS."
`(lambda (arg)
(imalison:compose-helper-unary ,funcs)))
(defmacro imalison:compose-helper-unary (funcs)
"Builds funcalls of FUNCS applied to the arg."
(if (equal (length funcs) 0)
'arg
`(funcall ,(car funcs) (imalison:compose-helper-unary ,(cdr funcs)))))
#+END_SRC
** prefix-alternatives
Prefix alternatives is a macro that builds a function that selects one of a collection of functions that are provided to the macro based on the value of the prefix argument.
#+BEGIN_SRC emacs-lisp