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Enclosing an expression with right single quotes ' ' will delay the evaluation of the expression.

As another example, help(Digits); returns a message stating that the argument to the help function was not a name --- because Digits evaluates to an integer value. To get the desired help description, use instead the quoted form: help('Digits');.

Enclosing an expression in unevaluation quotes produces a new expression of type uneval . It evaluates to the original expression.

After each evaluation, one level of single quotes is stripped off.

Note that evaluation is different from simplification.

A special case of unevaluation is used to unassign a name. In some cases, the evaln function is required to unassign a name, such as: $\mathrm{for}i\mathrm{to}n\mathrm{do}{a}_i:=\mathrm{evaln}\left(a_i\right)\mathrm{end}\mathrm{do};$ where i must be evaluated but $a_i$ must not be fully evaluated.

It is important to quote name arguments passed to procedures, such as type names, or options to other procedures.

There is also a procedure parameter modifier, uneval , which declares that an argument to a procedure is automatically left unevaluated.

$x≔2\:$

$y≔3\:$

$f≔'x+y'$

$f≔x+y$

$5$

$a≔1$

$a≔1$

$''a''$

$'a'$

$'a'$

$a$

$a$

$1$

$'2'$

$2$

$\mathrm{dependent}≔2\:$

$\mathrm{type}\left(s\,'\mathrm{dependent}\left(\left\{s\,t\right\}\right)'\right)$

$\mathrm{true}$

$\mathrm{type}\left(s\,\mathrm{dependent}\left(\left\{s\,t\right\}\right)\right)$

$\mathrm{false}$

$x≔5$

$x≔5$

$x≔'x'$

$x≔x$

$x$

$x$