A TS rule that matches on a pattern containing only wildcards fails:

Annotation(exp) :-
	where exp => String(_)

When compiling, I get this error:

match symbols in build pattern
	Build(Anno(Op("String",[Wld]),Op("Nil",[])))

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A workaround is to replace at least one wildcard by an unused variable:

Annotation(exp) :-
	where exp => String(x)

Submitted by D. Pelsmaeker on 7 July 2014 at 13:58

Added this workaround to the desugaring in TS, see PR 3.