Re-namespace general scheme code to bs

1 files changed, 72 insertions, 0 deletions

diff --git a/bs/string.scm b/bs/string.scm
new file mode 100644
index 0000000..b12bf00
--- /dev/null
+++ b/bs/string.scm
@@ -0,0 +1,72 @@
+(define-module (bs string)
+  #:export (replace replace-char to-string str capitalize split
+                    strip lstrip rstrip))
+
+(define (split s c)
+  (if s
+      (string-split s c)
+      #f))
+
+(define (replace-char s match repl)
+  (let ((f (lambda (a b)
+             (let ((next-char (if (eq? a match) repl a)))
+               (string-concatenate (list b (string next-char)))))))
+    (string-fold f "" s)))
+
+(define (replace s match repl)
+  (string-replace-substring s match repl))
+
+(define (to-string x)
+  (format #f "~a" x))
+
+(define str
+  (case-lambda
+    (() "")
+    ((x) (to-string x))
+    ((x . rest) (string-concatenate (map str (cons x rest))))))
+
+(define (capitalize s)
+  (let ((s (to-string s)))
+    (if (< (string-length s) 2)
+        (string-upcase s)
+        (str (string-upcase (substring s 0 1))
+             (substring s 1 )))))
+
+(define (strip s char)
+  (string-trim-both s char))
+
+(define (lstrip s char)
+  (string-trim s char))
+
+(define (rstrip s char)
+  (string-trim-right s char ))
+
+
+;;; {String Fun: string-replace-substring}
+;;;
+
+;; string-replace-substring By A. Wingo in
+;; https://lists.gnu.org/archive/html/guile-devel/2014-03/msg00058.html
+;; also in string-replace-substring guix:guix/utils.scm.
+
+(define (string-replace-substring str substring replacement)
+  "Return a new string where every instance of @var{substring} in string
+   @var{str} has been replaced by @var{replacement}. For example:
+
+   @lisp
+   (string-replace-substring \"a ring of strings\" \"ring\" \"rut\")
+   @result{} \"a rut of struts\"
+   @end lisp
+   "
+  (let ((sublen (string-length substring)))
+    (with-output-to-string
+      (lambda ()
+        (let lp ((start 0))
+          (cond
+           ((string-contains str substring start)
+            => (lambda (end)
+                 (display (substring/shared str start end))
+                 (display replacement)
+                 (lp (+ end sublen))))
+           (else
+            (display (substring/shared str start)))))))))