57 lines
2.1 KiB
Common Lisp
57 lines
2.1 KiB
Common Lisp
;;; lib.functions.lisp - 2025-02-09
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;; Copyright (C) 2025 Aryadev Chavali
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;; This program is distributed in the hope that it will be useful, but WITHOUT
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;; ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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;; FOR A PARTICULAR PURPOSE. See the GNU General Public License Version 2 for
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;; details.
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;; You may distribute and modify this code under the terms of the GNU General
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;; Public License Version 2, which you should have received a copy of along with
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;; this program. If not, please go to <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; Helpful functions for usage throughout the project.
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;;; Code:
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(in-package :cantedraw.lib.functions)
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(fn range (start end &optional (step 1)) (-> (fixnum fixnum &optional fixnum) list)
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"Make a list of numbers from START to END (exclusive). If STEP is given, then
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each member is STEP distance apart."
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(if (<= end start)
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(error (format nil "~a < ~a" end start))
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(loop :for i :from start :to (1- end) :by step
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:collect i)))
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(fn take (n lst) (-> (fixnum list) list)
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"Return the first N elements of LST."
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(subseq lst 0 n))
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(fn split (n lst) (-> (fixnum list) list)
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"Return CONS where CAR is the first N elements of LST and CDR is the rest."
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(cons (take n lst)
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(subseq lst n)))
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(fn rev-map (indicator lst &key (key-eq #'eq))
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(-> (function list &key (:key-eq function)) list)
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"Given LST and INDICATOR: LST -> A, return an association list A -> 2^LST
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where key x in A has associations {y in LST : INDICATOR(y) = x}."
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(loop :with assoc-list := nil
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:for element :in lst
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:for key := (funcall indicator element)
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:if (assoc key assoc-list :test key-eq)
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:do (->> (alist-val key assoc-list)
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(cons element)
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(setf (alist-val key assoc-list)))
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:else
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:do (setq assoc-list (cons (list key element) assoc-list))
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:finally (return assoc-list)))
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(fn parse-integer* (inp) (-> (string) (or integer list))
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"Given string INP, attempt to parse an integer. Return NIL otherwise."
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(parse-integer inp :junk-allowed t))
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