The Exists command returns true if a type is associated with the name typename via the TypeTools package, and false otherwise.

Note that the Exists command does not check whether a name is the name of a valid type, since built-in types and types created by assigning to the name type/typename are not recognized.

To determine whether a name is the name of a valid type, use type( typename, 'type' ).

${\mathrm{TypeTools}}_{\mathrm{AddType}}\left(\'\mathrm{tff}\'\,\'\left\{\mathrm{identical}\left(\mathrm{true}\right)\,\mathrm{identical}\left(\mathrm{false}\right)\,\mathrm{identical}\left(\mathrm{FAIL}\right)\right\}\'\right)$

${\mathrm{TypeTools}}_{\mathrm{Exists}}\left(\'\mathrm{tff}\'\right)$

$\mathrm{true}$

${\mathrm{TypeTools}}_{\mathrm{Exists}}\left(\'\mathrm{no\_such\_type\_\_}\'\right)$

$\mathrm{false}$

${\mathrm{TypeTools}}_{\mathrm{Exists}}\left(\'\mathrm{integer}\'\right)$

$\mathrm{false}$

$\mathrm{type}\left(\'\mathrm{integer}\'\,\'\mathrm{type}\'\right)$

$\mathrm{true}$