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Empty string: Difference between revisions
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=={{header|TXR}}==
====Pattern Matching====
<lang txr>@(bind a "")</lang>
If <code>a</code> is unbound, a binding is created, containing the empty string.
If <code>a</code> is already bound, <code>bind</code> succeeds if <code>a</code> contains the empty string, and the pattern matching continues at the next directive. Or else a failure occurs, triggering backtracking behavior.
====TXR Lisp====
<lang lisp>@(do (defvar *a* "")
(if (equal *a* "")
(format t "empty string\n"))
(set *a* "nonempty")
(if (zerop (length *a*))
(format t "guess what?\n")))</lang>
=={{header|TUSCRIPT}}==
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