Mercurial > lbo > hg > lispplay
view lists.lisp @ 0:81137f478b5c
initial examples and some of my own functions/macros
author | Lewin Bormann <lbo@spheniscida.de> |
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date | Fri, 04 Oct 2019 11:49:00 +0200 |
parents | |
children | a3dca97e5f3b |
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;; Reverse list (defun my-reverse (l) (if (= 0 (length l)) '() (append (my-reverse (cdr l)) (list (car l))))) (defun my-foldl (f init l) ;; tail-recursive but not lazy (if l (my-foldl f (funcall f init (car l)) (cdr l)) init)) (defun my-foldr (f l init) ;; lazy but not tail-recursive (if l (funcall f (car l) (my-foldr f (cdr l) init)))) (defun my-map (f l) (if l (cons (funcall f (car l)) (my-map f (cdr l))) nil)) (defun my-mapf (f l) (defun folder (acc e) (cons (funcall f e) acc)) (my-reverse (my-foldl #'folder nil l))) (defun my-range (from to) (defun _my-range (acc from to) ;; for tail recursion (if (eql from to) acc (_my-range (cons to acc) from (- to 1)))) (_my-range () (- from 1) (- to 1))) (defun my-append (a b) ;; not tail-recursive (if a (cons (car a) (my-append (cdr a) b)) b)) (defmacro my-dotimes ((var up-to) &rest body) `(mapcar #'(lambda (,var) ,@body) (my-range 0 ,up-to))) (defmacro my-let (bindings &rest body) (defun _names () (mapcar #'car bindings)) (defun _vals () (mapcar #'cadr bindings)) `(funcall #'(lambda (,@(_names)) ,@body) ,@(_vals))) (defmacro my-let* (bindings &rest body) (if (not bindings) `(funcall (lambda () ,@body)) `(my-let (,(car bindings)) (my-let* ,(cdr bindings) ,@body))))