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(*<*)theory Overloading = Overloading1:(*>*)
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instance list :: ("term")ordrel
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by intro_classes
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text{*\noindent
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This \isacommand{instance} declaration can be read like the declaration of
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11494
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a function on types. The constructor @{text list} maps types of class @{text
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term} (all HOL types), to types of class @{text ordrel};
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in other words,
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if @{text"ty :: term"} then @{text"ty list :: ordrel"}.
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Of course we should also define the meaning of @{text <<=} and
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@{text <<} on lists:
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*}
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defs (overloaded)
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prefix_def:
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"xs <<= (ys::'a::ordrel list) \<equiv> \<exists>zs. ys = xs@zs"
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strict_prefix_def:
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"xs << (ys::'a::ordrel list) \<equiv> xs <<= ys \<and> xs \<noteq> ys"
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(*<*)end(*>*)
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