
<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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