1 files changed, 43 insertions, 0 deletions
diff --git a/helpers.scm b/helpers.scm
new file mode 100644
index 00000000..717a10d4
--- /dev/null
+++ b/helpers.scm
@@ -0,0 +1,43 @@
+(use-modules (srfi srfi-1)
+             (srfi srfi-8) ; receive
+             )
+
+(define (nlist? l)
+  "Returns #t if l is a pair that is not a list."
+  (and (pair? l)
+       (not (list? l))))
+
+(define (flatten tree)
+  "Flattens tree, should only return propper lists."
+  (cond ((null? tree) '())
+        ((list? tree)
+         (if (null? (cdr tree))
+             (flatten (car tree))
+             (let ((ret (cons (flatten (car tree))
+                              (flatten (cdr tree)))))
+               (if (nlist? ret)
+                   (list (car ret) (cdr ret))
+                   ret))))
+        (else tree)))
+
+
+(define (map-lists f lst)
+  "Map f over lst, if (car lst) is a list, pass the list to f. If (car list)
+isn't a list, pass the rest of lst to f."
+  (cond ((null? lst) '())
+        ((list? (car lst)) (cons (f (car lst))
+                                 (map-lists f (cdr lst))))
+        (else (f lst))))
+
+(define (beautify tree)
+  "Takes a prefix tree and turns some characters to strings."
+  (define (helper branch)
+    (receive (head tail)
+        (span char? branch)
+      (cons (list->string head)
+            (beautify tail))))
+  (if (or (null? tree)
+          (not (list? tree)))
+      tree
+      (cons (beautify (car tree))
+            (map-lists helper (cdr tree)))))