8.8 Exercises

• Write a file SetAbs.oz containing a functor program for the set abstract datatype that you previously developed in an exercise (see Section 7.11). The functor should export the constructor procedure on feature new. Install ozmake on your computer and use it to compile SetAbs.oz to produce SetAbs.ozf. The shell command to achieve this is:

  ozmake --build SetAbs.ozf

  or more simply:

  ozmake SetAbs.ozf

  Verify that this worked by obtaining the SetAbs module in the OPI from file SetAbs.ozf using Module.link. Create a set. Add some elements. Check for membership, etc.

• Use ozmake to remove the compiled file SetAbs.ozf from your project directory. This can be achieved with the command:

  ozmake --clean

  Now write a makefile in file makefile.oz to describe this library. The library SetAbs.ozf should be installed at the abstract URI x-ozlib://oz-kurs/exercises/SetAbs.ozf (think what is the value of the makefile's uri feature needed in order to achieve this). The package offering this library should be identified by mogul:/oz-kurs/exercises/modprog (note that mogul: here is part of this abstract identifier, just like x-ozlib: above is part of the librarie's abstract URI). Invoke ozmake in order to build and install your package. The command for this is:

  ozmake --install

  You should now list the contents of your database of installed packages as follows:

  ozmake --list

  Now test that this worked by obtaining the SetAbs module in the OPI from its abstract URI:

  declare [MySetModule] = {Module.link ['x-ozlib://oz-kurs/exercises/SetAbs.ozf']}

  Create a set. Add some elements, etc.

• Rewrite the finite automaton code of Section 6.2 into a functor program FiniteAutomaton.oz which exports on feature accept one function:

  fun {Accept Automaton Word} ... end

  This function takes an Automaton as 1st argument and a Word as 2nd argument and returns true iff the Word is accepted by the Automaton. Your functor should import the library x-ozlib://oz-kurs/exercises/SetAbs.ozf that you installed in the previous exercise and use this abstraction in its code. Extend makefile.oz to state that FiniteAutomaton.ozf is also part of your package. Compile and install your package using the command:

  ozmake --upgrade

  what happens if instead you invoke ozmake --install and why? Test that your library works by getting your new FiniteAutomaton module with Module.link in the OPI. What is its abstract URI? Use it in the argument to Module.link. Test FiniteAutomaton.accept with some examples.

• Create a package file modprog.pkg for this little project. This is achieved with command:

  ozmake --create --package=modprog.pkg

  Verify that this worked by installing the package you just created:

  ozmake --upgrade --package=modprog.pkg

  Why do we use option --upgrade rather than --install? Now uninstall the package:

  ozmake --uninstall --package=mogul:/oz-kurs/exercises/modprog

  Why is the package argument here mogul:/oz-kurs/exercises/modprog rather than modprog.pkg? Verify that the library provided by the package is no longer available by attempting to obtain and use it in the OPI. Install it again from modprog.pkg and very that it is again available and works.