Magnar Sveen
14 years ago
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5 changed files with 197 additions and 140 deletions
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## !map `(fn list)` |
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Returns a new list consisting of the result of applying `fn` to the items in `list`. |
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```cl |
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(!map (lambda (num) (* num num)) (quote (1 2 3 4))) ;; => (quote (1 4 9 16)) |
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(!map (quote square) (quote (1 2 3 4))) ;; => (quote (1 4 9 16)) |
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(!!map (* it it) (quote (1 2 3 4))) ;; => (quote (1 4 9 16)) |
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``` |
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## !reduce-from `(fn initial-value list)` |
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Returns the result of applying `fn` to `initial-value` and the |
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first item in `list`, then applying `fn` to that result and the 2nd |
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item, etc. If `list` contains no items, returns `initial-value` and |
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`fn` is not called. |
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```cl |
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(!reduce-from (quote +) 7 (quote (1 2))) ;; => 10 |
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(!reduce-from (lambda (memo item) (+ memo item)) 7 (quote (1 2))) ;; => 10 |
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(!!reduce-from (+ acc it) 7 (quote (1 2 3))) ;; => 13 |
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``` |
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## !reduce `(fn list)` |
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Returns the result of applying `fn` to the first 2 items in `list`, |
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then applying `fn` to that result and the 3rd item, etc. If `list` |
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contains no items, `fn` must accept no arguments as well, and |
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reduce returns the result of calling `fn` with no arguments. If |
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`list` has only 1 item, it is returned and `fn` is not called. |
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```cl |
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(!reduce (quote +) (quote (1 2))) ;; => 3 |
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(!reduce (lambda (memo item) (format %s-%s memo item)) (quote (1 2 3))) ;; => 1-2-3 |
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(!!reduce (format %s-%s acc it) (quote (1 2 3))) ;; => 1-2-3 |
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``` |
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## !filter `(fn list)` |
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Returns a new list of the items in `list` for which `fn` returns a non-nil value. |
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```cl |
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(!filter (lambda (num) (= 0 (% num 2))) (quote (1 2 3 4))) ;; => (quote (2 4)) |
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(!filter (quote even?) (quote (1 2 3 4))) ;; => (quote (2 4)) |
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(!!filter (= 0 (% it 2)) (quote (1 2 3 4))) ;; => (quote (2 4)) |
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``` |
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## !remove `(fn list)` |
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Returns a new list of the items in `list` for which `fn` returns nil. |
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```cl |
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(!remove (lambda (num) (= 0 (% num 2))) (quote (1 2 3 4))) ;; => (quote (1 3)) |
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(!remove (quote even?) (quote (1 2 3 4))) ;; => (quote (1 3)) |
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(!!remove (= 0 (% it 2)) (quote (1 2 3 4))) ;; => (quote (1 3)) |
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``` |
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## !concat `(&rest lists)` |
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Returns a new list with the concatenation of the elements in |
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the supplied `lists`. |
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```cl |
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(!concat (quote (1))) ;; => (quote (1)) |
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(!concat (quote (1)) (quote (2))) ;; => (quote (1 2)) |
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(!concat (quote (1)) (quote (2 3)) (quote (4))) ;; => (quote (1 2 3 4)) |
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``` |
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## !mapcat `(fn list)` |
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Returns the result of applying concat to the result of applying map to `fn` and `list`. |
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Thus function `fn` should return a collection. |
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```cl |
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(!mapcat (quote list) (quote (1 2 3))) ;; => (quote (1 2 3)) |
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(!mapcat (lambda (item) (list 0 item)) (quote (1 2 3))) ;; => (quote (0 1 0 2 0 3)) |
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(!!mapcat (list 0 it) (quote (1 2 3))) ;; => (quote (0 1 0 2 0 3)) |
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``` |
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## !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 + |
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additional args. |
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```cl |
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(funcall (!partial (quote +) 5) 3) ;; => 8 |
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(funcall (!partial (quote +) 5 2) 3) ;; => 10 |
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``` |
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## !difference `(list list2)` |
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Return a new list with only the members of `list` that are not in LIST2. |
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The test for equality is done with `equal`, |
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or with `!compare-fn` if that's non-nil. |
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```cl |
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(!difference (quote nil) (quote nil)) ;; => (quote nil) |
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(!difference (quote (1 2 3)) (quote (4 5 6))) ;; => (quote (1 2 3)) |
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(!difference (quote (1 2 3 4)) (quote (3 4 5 6))) ;; => (quote (1 2)) |
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``` |
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## !intersection `(list list2)` |
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Return a new list containing only the elements that are members of both `list` and LIST2. |
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The test for equality is done with `equal`, |
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or with `!compare-fn` if that's non-nil. |
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```cl |
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(!intersection (quote nil) (quote nil)) ;; => (quote nil) |
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(!intersection (quote (1 2 3)) (quote (4 5 6))) ;; => (quote nil) |
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(!intersection (quote (1 2 3 4)) (quote (3 4 5 6))) ;; => (quote (3 4)) |
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``` |
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## !uniq `(list)` |
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Return a new list with all duplicates removed. |
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The test for equality is done with `equal`, |
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or with `!compare-fn` if that's non-nil. |
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```cl |
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(!uniq (quote nil)) ;; => (quote nil) |
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(!uniq (quote (1 2 2 4))) ;; => (quote (1 2 4)) |
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``` |
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## !contains? `(list element)` |
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Return whether `list` contains `element`. |
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The test for equality is done with `equal`, |
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or with `!compare-fn` if that's non-nil. |
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```cl |
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(!contains? (quote (1 2 3)) 1) ;; => t |
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(!contains? (quote (1 2 3)) 2) ;; => t |
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(!contains? (quote (1 2 3)) 4) ;; => nil |
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``` |
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@ -0,0 +1,20 @@ |
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## License |
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Copyright (C) 2012 Magnar Sveen, Joel McCracken |
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Authors: Magnar Sveen <magnars@gmail.com> |
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Joel McCracken |
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Keywords: lists |
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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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@ -0,0 +1,27 @@ |
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# bang.el [](http://travis-ci.org/magnars/bang.el) |
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The startings of a modern list api for Emacs. Does not require 'cl. |
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We're looking to Clojure for naming and signatures. |
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## Warning |
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This is so much a work in progress that you should definitely not be using it yet. |
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## Anaphoric functions |
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While `!filter` takes a function to filter the list by, you can also use the |
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anaphoric form with double bangs - which will then be executed with `it` exposed |
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as the list item. Here's an example: |
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(!filter (lambda (num) (= 0 (% num 2))) '(1 2 3 4)) ;; normal version |
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(!!filter (= 0 (% it 2)) '(1 2 3 4)) ;; anaphoric version |
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of course the original can also be written like |
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(defun even? (num) (= 0 (% num 2))) |
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(!filter even? '(1 2 3 4)) |
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which demonstrates the usefulness of both versions. |
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