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doc-src/Tutorial/Datatype/lookup
author paulson
Mon, 31 Jan 2000 16:13:28 +0100
changeset 8172 988a7737e158
parent 5851 15ce4c1c8313
permissions -rw-r--r--
Pi_empty1 is a more general simprule than empty_fun

consts   lookup :: ('a,'v)trie => 'a list => 'v option
primrec "lookup t [] = value t"
        "lookup t (a#as) = (case assoc (alist t) a of
                              None => None
                            | Some at => lookup at as)"
isabelle