[r2003-07-29 14:20:20 by cvscast] Empty log message

Original author: cvscast
Date: 2003-07-29 14:20:20+00:00

driver/examples.ml

@@ -352,6 +352,43 @@ let doc : Xhtml =
 bold [doc];;
 
 let [x] = bold [doc] in print_xml x;;
+";"reference","(* In CDuce the expression  \"ref T exp\" returns a reference  *)
+(* to the result of \"exp\" and has type \"ref T\" provided that *)
+(* \"exp\" is of type \"T\". References come equipped with three *)
+(* operators: \":=\" (assignment), \"!\" (dereferencing), and \";\"*) 
+(* (sequencing).                                             *)
+
+
+let stack = ref [Int*] []
+
+let fun push(x : Int) : []  = 
+  stack := [x !!stack]
+
+let fun pop ([] : []) : Int = 
+  match !stack with [x ;y] -> stack := y; x | _ -> raise \"Empty stack\"
+
+
+(* In [ pattern  ;y] the variable y captures the rest of the *)
+(* sequence. It is equivalent to [pattern y::_*]             *)
+(*                                                           *)
+(* Since sequences are encoded by pairs, we could write      *)
+(* the following [deprecated] equivalent definitions         *)
+(*
+let fun push(x : Int) : []  = 
+  stack := (x, !stack)
+let fun pop ([] : []) : Int = 
+  match !stack with (x, y) -> stack := y; x | _ -> raise \"Empty stack\"
+*)
+
+;;
+
+push 1;;
+push 2;;
+push 3;;
+pop [];;
+pop [];;
+pop [];;
+pop [];;
 "; ]
 let present = "<ul><li><a href=\"/cgi-bin/cduce?example=xml\">XML elements.</a> 
 XML elements.
@@ -377,4 +414,6 @@ The good old XML bibliography example.
 Syntactic sugar for projection.
 </li><li><a href=\"/cgi-bin/cduce?example=xtransform\">Tree transformations.</a> 
 How to perform XSLT-like transformations.
+</li><li><a href=\"/cgi-bin/cduce?example=reference\">References.</a> 
+Mutable values.
 </li></ul>"
\ No newline at end of file