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;;;; l-system.lisp
(in-package #:l-system)
;;; "l-system" goes here. Hacks and glory await!
(defparameter *l-system-clauses* (make-hash-table :test 'eq))
(defun l-system (axiom depth)
(iter (repeat depth)
(with result = axiom)
(setf result
(map-l-system result))
(finally (return result))))
(defun map-l-system (clauses)
(iter (for clause in clauses)
(appending (let ((func (gethash (car clause) *l-system-clauses*)))
(if (functionp func)
(let ((result (apply func
(rest clause))))
(when result
result))
(list clause))))))
(defun setf-l-system-rule (symbol lambda)
(setf (gethash symbol *l-system-clauses*)
lambda))
(defun make-l-system-expr (item)
`(list ',(first item) ,(second item)))
(defun make-l-system-list (rest)
(iter (for item in rest)
(collecting (make-l-system-expr item))))
(defmacro make-l-system-rule (vars &body body)
`#'(lambda ,vars (list ,@(make-l-system-list body))))
(defmacro -> (symbol vars &body body)
`(setf-l-system-rule ',symbol
(make-l-system-rule ,vars ,@body)))
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