In some circumstances, it may be necessary for module members to "know" what module they belong to. For this reason, you can create a named module, using a slightly modified syntactic form of a module definition. It differs from the ordinary syntax only in the placement of a name between the module keyword and the parentheses that follow it.

Evaluating a named module definition causes, as a side effect, the assignment of the resulting module to the name, and the module name is stored in the attributes of each module member.

Note: This causes the specified name to be protected. Thus, evaluating a global named module definition more than once will generate an error. Evaluating a local definition in separate invocations of a procedure will produce multiple named modules, each with a separate (but identical looking) protected name.

Named modules are also used by the system for some purposes. Every module that is saved to a repository is given a name (that under which it was saved) for use by the persistent store.

The name of a named module, written as a string, can also be used as the first argument to the `module`(...) type. This indicates that the type should only match modules that have the specified name.

$\mathbf{module}\mathrm{MyModule}\left(\right)\mathrm{\_export}\left(e\right)\;e≔2\mathbf{end\; module}$

$\mathbf{module}\mathrm{MyModule}\left(\right)\mathbf{export}e\;\mathbf{end\; module}$

$\mathrm{MyModule}:-e$

$2$

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

$\mathrm{true}$

$\mathbf{module}\mathrm{aModule}\left(\right)\mathbf{end\; module}$

$\mathbf{module}\mathrm{aModule}\left(\right)\mathbf{end\; module}$

$\mathbf{module}\mathrm{aModule}\left(\right)\mathbf{end\; module}$

Error, (in aModule) attempting to assign to `aModule` which is protected.  Try declaring `local aModule`; see ?protect for details.

$\mathbf{module}\mathrm{NamedModule}\left(\right)\mathrm{\_export}\left(\mathrm{e1}\right)\mathbf{end\; module}\:$

$\mathbf{use}\mathrm{NamedModule}\mathbf{in}\mathrm{e1}\mathbf{end\; use}$

$\mathrm{NamedModule}:-\mathrm{e1}$

$\mathrm{UnNamedModule}≔\mathbf{module}\left(\right)\mathrm{\_export}\left(\mathrm{e2}\right)\mathbf{end\; module}\:$

$\mathbf{use}\mathrm{UnNamedModule}\mathbf{in}\mathrm{e2}\mathbf{end\; use}$

$\mathrm{e2}$

make := proc(x)
    local Number;
    module Number() export n; end module;
    Number:-n := x;
    Number
end proc:

$\mathrm{num1}≔\mathrm{make}\left(2\right)$

$\mathrm{num1}≔\mathbf{module}\mathrm{Number}\left(\right)\mathbf{export}n\;\mathbf{end\; module}$

$\mathrm{num2}≔\mathrm{make}\left(3.5\right)$

$\mathrm{num2}≔\mathbf{module}\mathrm{Number}\left(\right)\mathbf{export}n\;\mathbf{end\; module}$

$\mathrm{type}\left(\mathrm{num1}\,'\mathrm{`module`}'\left(''Number''\right)\right)$

$\mathrm{true}$

$\mathrm{type}\left(\mathrm{num2}\,'\mathrm{`module`}'\left(''Number''\,n::\'\mathrm{integer}\'\right)\right)$

$\mathrm{false}$