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--- magistraleinformaticanetworking:spm:ocamlfs1 [23/03/2011 alle 16:25 (14 anni fa)] – Marco Danelutto
+++ magistraleinformaticanetworking:spm:ocamlfs1 [23/03/2011 alle 16:31 (14 anni fa)] (versione attuale) – Marco Danelutto
@@ Linea 93: / Linea 93: @@
 # main stream;;
 - : int array list = [[|1; 4|]; [|9; 16|]]
+#
+</code>
+Even better, we can define our data type **stream** using the Ocaml type definition syntax:
+<code>
+# type 'a stream = Empty | Stream of ('a * 'a stream);;
+type 'a stream = Empty | Stream of ('a * 'a stream)
+#
+</code>
+The farm functional semantics may therefore be defined by the function:
+<code>
+#
+  let rec farm f = function
+    Empty -> Empty
+  | Stream(x,y) -> Stream ((f x), (farm f y));;
+val farm : ('a -> 'b) -> 'a stream -> 'b stream = <fun>
+#
+</code>
+Therefore the type of our //farm of map// will be correctly inferred as:
+<code>
+# farm (Array.map sq);;
+- : int array stream -> int array stream = <fun>
 #
 </code>