Substring functions; fix a nasty MonoReduce pattern match substitution bug

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/ur/string.ur b/lib/ur/string.ur
index 23670966..e6d5903e 100644
--- a/lib/ur/string.ur
+++ b/lib/ur/string.ur
@@ -5,3 +5,14 @@ val append = Basis.strcat
 
 val sub = Basis.strsub
 val suffix = Basis.strsuffix
+
+val index = Basis.strindex
+val atFirst = Basis.strchr
+
+fun substring s {Start = start, Len = len} = Basis.substring s start len
+
+fun split s ch =
+    case index s ch of
+        None => None
+      | Some i => Some (substring s {Start = 0, Len = i},
+                        substring s {Start = i + 1, Len = length s - i - 1})