@@ -150,13 +150,14 @@ There are a few compatibility functions with Haskell's Prelude. Currently, the following are implemented: * BREAK* -* CYCLE (and its destructive variant NCYCLE). +* CYCLE (and its destructive version NCYCLE). * CURRY * DROP * DROP-WHILE * FILTER (more general than its Haskell counterpart). * FLIP * INSERT +* INTERSPERSE (and its destructive version NINTERSPERSE). * REPLICATE * SCAN* (using the key parameters :initial-value and :from-end it works as scanl, scanl1, scanr or scanr1) @@ -175,6 +176,41 @@ DESCRIBE or C-c C-d d in SLIME) and also http://undergraduate.csse.uwa.edu.au/units/230.301/lectureNotes/tourofprelude.html[A tour of the Haskell's prelude] to see more use cases. +Unfolding +^^^^^^^^^ + +There's an implementation of UNFOLD and UNFOLD-RIGHT as specified in +http://srfi.schemers.org/srfi-1/srfi-1.html#unfold[SRFI 1: List +library] + +Here's an example of UNFOLD: + +-------------------------------------------------------------------------- + (defun euler (f x0 y0 interval h) + "Computes an approximate solution of the differential equation + + y' = f(x, y), x in interval; y(x0) = y0 + + using Euler's explicit method. Interval is a list of two elements + representing a closed interval. The function returns a list of + points and the values of the approximate solution at those points. + + For example, + + EULER> (euler (lambda (x y) + (declare (ignore y)) + (- (sin x))) + 0 1 (list 0 (/ pi 2)) 0.5) + ((0 1) (0.5 1.0) (1.0 0.7602872) (1.5 0.33955175))" + (assert (<= (first interval) (second interval))) + (unfold (lambda (x) (> (first x) (second interval))) + #'identity + (lambda (pair) + (destructuring-bind (x y) pair + (list (+ x h) (+ y (* h (funcall f x y)))))) + (list x0 y0))) +------------------------------------------------------------------------- + Hash table utilities ^^^^^^^^^^^^^^^^^^^^ README @@ -25,6 +25,9 @@ (defun string-join (list &optional (sep " ")) "Returns a string joining each string in LIST by SEP. If SEP is not specified, the default separator is a space." + ;; TODO This should use intersperse as soon as it works with + ;; arbitrary sequences. + ;; Based on Pascal Costanza's approach at ;; http://groups.google.com/group/comp.lang.lisp/msg/8adbef3a067ece78 (when list string.lisp cca6a3f64295c735a762662b2b4fa58f0ba7df87 Juan M. Bello Rivas jmbr@superadditive.com http://github.com/jmbr/incf-cl/commit/3ac765cf6b6cfcea7214cd99ee239088ce88a536 3ac765cf6b6cfcea7214cd99ee239088ce88a536 2007-12-14T11:59:46-08:00 2007-12-14T11:59:46-08:00 Updated documentation. 04a7413f6eaa168c11ff4c684e2b78a431f12460 Juan M. Bello Rivas jmbr@superadditive.com