The IsPackageInstalled command returns false if the installation bundle with the given package_id is not installed, otherwise it returns information about the installed package as specified by the output option.  

The first argument in the calling sequence can be a string representing the "title" or "id" number of the given package.  A match is found by iterating through the output of PackageTools:-ListInstalledPackages.

By default output = version; which, when the package is found will return a string indicating the version of the given package. The title, id and path output variants will return a string with the specified property. Using output=Record will give you a Record containing all of these properties. Similarly output=JSON will give a JSON formatted string containing all of the properties.

This command is intended to work with the notion of "package" pertaining to installation-bundles.  To find traditional maple-based package modules that are installed, try using with or assigned.  To find the source library that contains a package-module, use the LibraryTools:-FindLibrary command.

The primary use of this function is for behind-the-scenes work interfacing with the GUI to assist with installation and package management.

$\mathrm{with}\left(\mathrm{PackageTools}\right)\:$

$\mathrm{IsPackageInstalled}\left(''1234''\right)$

$\mathrm{mypacks}≔\mathrm{PackageTools}:-\mathrm{ListInstalledPackages}\left(\mathrm{output}=\mathrm{Record}\right)$

$\mathrm{map}\left(x\mapsto \mathrm{PackageTools}:-\mathrm{IsPackageInstalled}\left(x\left[\mathrm{id}\right]\right)\,\mathrm{mypacks}\right)$

$\mathrm{IsPackageInstalled}\left(''1234''\,'\mathrm{output}'=\mathrm{Record}\right)$

The PackageTools[IsPackageInstalled] command was introduced in Maple 2017.

For more information on Maple 2017 changes, see Updates in Maple 2017.