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cl:constant_variables:t [2019/10/13 03:00]
cl:constant_variables:t [2019/10/14 06:00] (current)
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 +====== Constant Variable T ======
 +
 +====Constant Value====
 +**t**.
 +
 +====Description====
 +The //​[[CL:​Glossary:​boolean]]//​ representing true, and the canonical //​[[CL:​Glossary:​generalized boolean]]// representing true. Although any //​[[CL:​Glossary:​object]]//​ other than **[[CL:​Constant Variables:​nil]]** is considered //​[[CL:​Glossary:​true]]//,​ **t** is generally used when there is no special reason to prefer one such //​[[CL:​Glossary:​object]]//​ over another.
 +
 +The //​[[CL:​Glossary:​symbol]]//​ **t** is also sometimes used for other purposes as well. For example, as the //​[[CL:​Glossary:​name]]//​ of a //​[[CL:​Glossary:​class]]//,​ as a //​[[CL:​Glossary:​designator]]//​ (//e.g.// a //​[[CL:​Glossary:​stream designator]]//​) or as a special symbol for some syntactic reason (//e.g.// in **[[CL:​Macros:​case]]** and **[[CL:​Macros:​typecase]]** to label the //​otherwise-clause//​).
 +
 +====Examples====
 +<​blockquote> ​
 +t <r>T </r>
 +([[CL:​Functions:​eq]] t 't) <​r>//​[[CL:​Glossary:​true]]//​ </r>
 +([[CL:​Functions:​find-class]] 't) <​r>#<​CLASS T 610703333>​ </r>
 +([[CL:​Macros:​case]] 'a (a 1) (t 2)) <r>1 </r>
 +([[CL:​Macros:​case]] 'b (a 1) (t 2)) <r>2 </r>
 +([[CL:​Functions:​prin1]] 'hello t)
 +<​o>​HELLO </o>
 +<​r>​HELLO </r>
 +</​blockquote>​
 +
 +====See Also====
 +  * **[[CL:​Constant Variables:​nil]]**
 +
 +====Notes====
 +None.
 +