diff options
Diffstat (limited to 'module/hnh/util.scm')
| -rw-r--r-- | module/hnh/util.scm | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/module/hnh/util.scm b/module/hnh/util.scm index 759cdd48..c88a029e 100644 --- a/module/hnh/util.scm +++ b/module/hnh/util.scm @@ -17,6 +17,7 @@ find-extreme find-min find-max filter-sorted != + init+last take-to string-take-to string-first @@ -150,9 +151,12 @@ +;; TODO this is called flip in Haskell land (define (swap f) (lambda args (apply f (reverse args)))) - +;; Swap would be +;; (define (swap p) +;; (xcons (car p) (cdr p))) ;; Allow set to work on multiple values at once, ;; similar to Common Lisp's @var{setf} @@ -253,6 +257,12 @@ ;; (define (!= a b) (not (= a b))) (define != (negate =)) + +(define (init+last l) + (let ((last rest (car+cdr (reverse l)))) + (values (reverse rest) last))) + + (define (take-to lst i) "Like @var{take}, but might lists shorter than length." (if (> i (length lst)) @@ -396,7 +406,7 @@ (reverse (cons (map list last) rest )))))) ;; Given an arbitary tree, do a pre-order traversal, appending all strings. -;; non-strings allso allowed, converted to strings and also appended. +;; non-strings also allowed, converted to strings and also appended. (define (string-flatten tree) (cond [(string? tree) tree] [(list? tree) (string-concatenate (map string-flatten tree))] |