--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lab3/tree.mli	Thu Oct 05 08:04:15 2017 +0100
@@ -0,0 +1,45 @@
+(* lab3/tree.mli *)
+(* Copyright (c) 2017 J. M. Spivey *)
+
+open Dict
+
+(* |name| -- type for applied occurrences with annotations *)
+type name = 
+  { x_name: ident;              (* Name of the reference *)
+    x_line: int;                (* Line number *)
+    mutable x_def: def option}  (* Definition in scope *)
+
+type expr = 
+    Constant of int
+  | Variable of name
+  | Monop of Keiko.op * expr
+  | Binop of Keiko.op * expr * expr
+  | Call of name * expr list
+
+type stmt =
+    Skip
+  | Seq of stmt list
+  | Assign of name * expr
+  | Return of expr
+  | IfStmt of expr * stmt * stmt
+  | WhileStmt of expr * stmt
+  | Print of expr
+  | Newline
+
+type block = Block of ident list * proc list * stmt
+
+and proc = Proc of name * ident list * block
+
+type program = Program of block
+
+
+(* seq -- neatly join a list of statements into a sequence *)
+val seq : stmt list -> stmt
+
+val makeName : ident -> int -> name
+
+(* |get_def| -- rerieve definition from name *)
+val get_def : name -> def
+
+(* |print_tree| -- pretty-print a tree *)
+val print_tree : out_channel -> program -> unit