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+;;; 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)))