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;;; dash-functional.el --- Collection of useful combinators for Emacs Lisp -*- lexical-binding: t -*- |
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;; Copyright (C) 2013 Magnar Sveen |
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;; Author: Magnar Sveen <magnars@gmail.com> |
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;; Keywords: lisp functions combinators |
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;; This program is free software; you can redistribute it and/or modify |
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;; it under the terms of the GNU General Public License as published by |
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;; the Free Software Foundation, either version 3 of the License, or |
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;; (at your option) any later version. |
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;; This program is distributed in the hope that it will be useful, |
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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;; GNU General Public License for more details. |
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;; You should have received a copy of the GNU General Public License |
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;; along with this program. If not, see <http://www.gnu.org/licenses/>. |
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;;; Commentary: |
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;; Collection of useful combinators for Emacs Lisp |
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;; |
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;; See documentation on https://github.com/magnars/dash.el#functions |
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;;; Code: |
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(defun -partial (fn &rest args) |
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"Takes a function FN and fewer than the normal arguments to FN, |
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and returns a fn that takes a variable number of additional ARGS. |
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When called, the returned function calls FN with ARGS first and |
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then additional args." |
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(apply 'apply-partially fn args)) |
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(defun -rpartial (fn &rest args) |
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"Takes a function FN and fewer than the normal arguments to FN, |
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and returns a fn that takes a variable number of additional ARGS. |
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When called, the returned function calls FN with the additional |
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args first and then ARGS. |
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Requires Emacs 24 or higher." |
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(lambda (&rest args-before) (apply fn (append args-before args)))) |
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(defun -juxt (&rest fns) |
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"Takes a list of functions and returns a fn that is the |
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juxtaposition of those fns. The returned fn takes a variable |
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number of args, and returns a list containing the result of |
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applying each fn to the args (left-to-right). |
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Requires Emacs 24 or higher." |
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(lambda (&rest args) (mapcar (lambda (x) (apply x args)) fns))) |
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(defun -applify (fn) |
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"Changes an n-arity function FN to a 1-arity function that |
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expects a list with n items as arguments" |
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(apply-partially 'apply fn)) |
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(defun -on (operator transformer) |
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"Return a function of two arguments that first applies |
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TRANSFORMER to each of them and then applies OPERATOR on the |
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results (in the same order). |
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In types: (b -> b -> c) -> (a -> b) -> a -> a -> c" |
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(lambda (x y) (funcall operator (funcall transformer x) (funcall transformer y)))) |
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(defun -flip (func) |
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"Swap the order of arguments for binary function FUNC. |
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In types: (a -> b -> c) -> b -> a -> c" |
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(lambda (x y) (funcall func y x))) |
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(defun -const (c) |
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"Return a function that returns C ignoring any additional arguments. |
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In types: a -> b -> a" |
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(lambda (&rest args) c)) |
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(defmacro -cut (&rest params) |
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"Take n-ary function and n arguments and specialize some of them. |
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Arguments denoted by <> will be left unspecialized. |
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See SRFI-26 for detailed description." |
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(let* ((i 0) |
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(args (mapcar (lambda (x) (setq i (1+ i)) (make-symbol (format "D%d" i))) |
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(-filter (-partial 'eq '<>) params)))) |
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`(lambda ,args |
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,(--map (if (eq it '<>) (pop args) it) params)))) |
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(defun -not (pred) |
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"Take an unary predicates PRED and return an unary predicate |
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that returns t if PRED returns nil and nil if PRED returns |
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non-nil." |
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(lambda (x) (not (funcall pred x)))) |
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(defun -orfn (&rest preds) |
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"Take list of unary predicates PREDS and return an unary |
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predicate with argument x that returns non-nil if at least one of |
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the PREDS returns non-nil on x. |
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In types: [a -> Bool] -> a -> Bool" |
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(lambda (x) (-any? (-cut funcall <> x) preds))) |
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(defun -andfn (&rest preds) |
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"Take list of unary predicates PREDS and return an unary |
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predicate with argument x that returns non-nil if all of the |
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PREDS returns non-nil on x. |
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In types: [a -> Bool] -> a -> Bool" |
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(lambda (x) (-all? (-cut funcall <> x) preds))) |
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(provide 'dash-functional) |
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;;; dash-functional.el ends here |
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@ -0,0 +1,5 @@ |
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(define-package |
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"dash" |
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"1.8.0" |
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"A modern list library for Emacs." |
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'()) |
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