Substring functions; fix a nasty MonoReduce pattern match substitution bug

3 files changed, 21 insertions, 0 deletions

diff --git a/lib/ur/basis.urs b/lib/ur/basis.urs
index c63c5ed4..d70ccc24 100644
--- a/lib/ur/basis.urs
+++ b/lib/ur/basis.urs
@@ -57,6 +57,9 @@ val strlen : string -> int
 val strcat : string -> string -> string
 val strsub : string -> int -> char
 val strsuffix : string -> int -> string
+val strchr : string -> char -> option string
+val strindex : string -> char -> option int
+val substring : string -> int -> int -> string
 
 class show
 val show : t ::: Type -> show t -> t -> string
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})
diff --git a/lib/ur/string.urs b/lib/ur/string.urs
index ef522387..097a423f 100644
--- a/lib/ur/string.urs
+++ b/lib/ur/string.urs
@@ -6,3 +6,10 @@ val append : t -> t -> t
 
 val sub : t -> int -> char
 val suffix : t -> int -> string
+
+val index : t -> char -> option int
+val atFirst : t -> char -> option string
+
+val substring : t -> {Start : int, Len : int} -> string
+
+val split : t -> char -> option (string * string)