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55 | <H1><A NAME="SECTION0071200000000000000000"></A><A NAME="exprlists"></A> | |
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57 | 5.12 Expression lists | |
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61 | <dl><dd class="grammar"> | |
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63 | <table> | |
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65 | <td><a id='tok-expression_list' xml:id='tok-expression_list'>expression_list</a></td> | |
66 | <td>::=</td> | |
67 | <td><a class='grammartoken' href="Booleans.html#tok-expression">expression</a> ( "," <a class='grammartoken' href="Booleans.html#tok-expression">expression</a> )* [","]</td></tr> | |
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70 | <a class="grammar-footer" | |
71 | href="grammar.txt" type="text/plain" | |
72 | >Download entire grammar as text.</a> | |
73 | </dd></dl> | |
74 | ||
75 | <P> | |
76 | An expression list containing at least one comma yields a | |
77 | tuple. The length of the tuple is the number of expressions in the | |
78 | list. The expressions are evaluated from left to right. | |
79 | <a id='l2h-447' xml:id='l2h-447'></a> | |
80 | <P> | |
81 | The trailing comma is required only to create a single tuple (a.k.a. a | |
82 | <em>singleton</em>); it is optional in all other cases. A single | |
83 | expression without a trailing comma doesn't create a | |
84 | tuple, but rather yields the value of that expression. | |
85 | (To create an empty tuple, use an empty pair of parentheses: | |
86 | <code>()</code>.) | |
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