2 files changed, 147 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
@@ -0,0 +1,56 @@
+;;; 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))
diff --git a/lib/macros.lisp b/lib/macros.lisp
new file mode 100644
index 0000000..d182ce0
--- /dev/null
+++ b/lib/macros.lisp
@@ -0,0 +1,91 @@
+;;; lib.macros.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 macros for usage throughout the project.
+
+;;; Code:
+
+(in-package :cantedraw.lib.macros)
+
+(defmacro --> (placeholder &body forms)
+  "Lexically bind current form as `placeholder' for use in the next form, returning
+the result of the last form.
+
+i.e.
+
+(--> (a1 a2...) (b1 b2...) (c1 c2...)) =
+(let* ((placeholder (a1 a2 ...))
+       (placeholder (b1 b2 ...))
+       (placeholder (c1 c2 ...)))
+    _ )
+
+Also includes transformer where symbols are considered unary functions i.e.
+(--> x y) <-> (--> x (y placeholder)).
+"
+  (if (null forms)
+      nil
+      (let ((assignment-forms
+              (loop :for f :in forms
+                    :for canon-f := (if (symbolp f)
+                                        (list f placeholder)
+                                        f)
+                    :collect `(,placeholder ,canon-f))))
+        `(let* ,assignment-forms
+           ,placeholder))))
+
+(defmacro ->> (&rest forms)
+  "Make current form the last argument of the next form, returning the last
+  form.
+
+i.e.
+(->> (a1 a2...) (b1 b2...) (c1 c2...)) == (c1 c2 ... (b1 b2 ... (a1 a2 ...)))
+
+Also includes transformer where symbols are considered unary functions.
+
+Like the `|>' operator in Ocaml."
+  (if (null forms)
+      nil
+      (loop :with acc = (car forms)
+            :for func :in (cdr forms)
+            :for canon-func = (if (symbolp func) (list func) func)
+            :do (setq acc (append canon-func (list acc)))
+            :finally (return acc))))
+
+(defmacro while (condition &body body)
+  `(loop :while ,condition
+         :do
+         (progn ,@body)))
+
+(deftype -> (args result)
+  "Type alias for function."
+  `(function ,args ,result))
+
+(defmacro fn (name lambda-list type &body body)
+  "Construct a function `NAME' with a declared function type `TYPE' that takes
+arguments `LAMBDA-LIST' with body `BODY'."
+  `(progn
+     (declaim (ftype ,type ,name))
+     (defun ,name ,lambda-list
+       ,@body)))
+
+(defmacro $ (&rest forms)
+  "Given a sequence of FORMS, return a unary function which applies each form
+sequentially"
+  `(lambda (x)
+     (->> x ,@forms)))
+
+(defmacro alist-val (key alist)
+  "Helper macro for getting the value of KEY in ALIST."
+  `(cdr (assoc ,key ,alist)))