Split source code into different modules for cleanliness

1 files changed, 56 insertions, 0 deletions

diff --git a/lib/functions.lisp b/lib/functions.lisp
new file mode 100644
index 0000000..99796c9
--- /dev/null
+++ b/lib/functions.lisp
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+;;; lib.functions.lisp - 2025-02-09
+
+;; Copyright (C) 2025 Aryadev Chavali
+
+;; This program is distributed in the hope that it will be useful, but WITHOUT
+;; ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+;; FOR A PARTICULAR PURPOSE.  See the GNU General Public License Version 2 for
+;; details.
+
+;; You may distribute and modify this code under the terms of the GNU General
+;; Public License Version 2, which you should have received a copy of along with
+;; this program.  If not, please go to <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Helpful functions for usage throughout the project.
+
+;;; Code:
+
+(in-package :cantedraw.lib.functions)
+
+(fn range (start end &optional (step 1)) (-> (fixnum fixnum &optional fixnum) list)
+  "Make a list of numbers from START to END (exclusive).  If STEP is given, then
+each member is STEP distance apart."
+  (if (<= end start)
+      (error (format nil "~a < ~a" end start))
+      (loop :for i :from start :to (1- end) :by step
+            :collect i)))
+
+(fn take (n lst) (-> (fixnum list) list)
+  "Return the first N elements of LST."
+  (subseq lst 0 n))
+
+(fn split (n lst) (-> (fixnum list) list)
+  "Return CONS where CAR is the first N elements of LST and CDR is the rest."
+  (cons (take n lst)
+        (subseq lst n)))
+
+(fn rev-map (indicator lst &key (key-eq #'eq))
+    (-> (function list &key (:key-eq function)) list)
+  "Given LST and INDICATOR: LST -> A, return an association list A -> 2^LST
+where key x in A has associations {y in LST : INDICATOR(y) = x}."
+  (loop :with assoc-list := nil
+        :for element :in lst
+        :for key := (funcall indicator element)
+        :if (assoc key assoc-list :test key-eq)
+          :do (->> (alist-val key assoc-list)
+                   (cons element)
+                   (setf (alist-val key assoc-list)))
+        :else
+          :do (setq assoc-list (cons (list key element) assoc-list))
+        :finally (return assoc-list)))
+
+(fn parse-integer* (inp) (-> (string) (or integer list))
+  "Given string INP, attempt to parse an integer.  Return NIL otherwise."
+  (parse-integer inp :junk-allowed t))