<A NAME=Free_Variable>
<TITLE>Free_Variable</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>
<B>FREE VARIABLE</B> _ _ _ _ _ _ _ _ _ _ _ _ <B>type</B><P>
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A variable preceded by a tilde is considered as <em>free variable</em>
and stands for an arbitrary part in an algebraic form during
pattern matching. Free variables occur in the left-hand sides
of
<A HREF=r37_0060.html>rule</A>s, in the side relations for
<A HREF=r37_0641.html>compact</A>
and in the first arguments of
<A HREF=r37_0163.html>map</A> and
<A HREF=r37_0177.html>select</A>
calls. See
<A HREF=r37_0060.html>rule</A> for examples.
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In rules also
<A HREF=r37_0062.html>optional free variable</A>s may occur.
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