(C) Ralf Lämmel, Andrei Varanovich, University of Koblenz Landau

Logistics

• Course site
• Date published: 13 Nov 2013
• Deadline SVN: 19 Nov 2013 (End of Day)
• Other logistics as previously

Assignment

Option 1

Start from the following code from the lecture:

https://github.com/rlaemmel/pltcourse/blob/master/src/lecture-logs/unikold1314/while.pro

Improve well-typedness/-formedness to also ensure that variables are never accessed in expressions, if they were not previously initialized.

For instance, the following statement should be rejected:

write x;

Option 2

Start from the following code from the lecture:

https://github.com/rlaemmel/pltcourse/blob/master/src/lecture-logs/unikold1314/fl.pro

Add a well-formedness predicate so that FL programs are checked as follows. i) All function applications refer to function names that are actually defined. ii) In the body of a function definition, all variable references refer to parameters of the enclosing function definition.

For instance, the following function definition should be rejected because i) is violated:

 (
    [
      ( 
        f,
        [x], 
        apply(
          g,
          [const(42)]
        )
      )
    ],
    apply(f, [const(88)])
  )

The following function definition should be rejected because ii) is violated:

 (
    [
      ( 
        f,
        [x], 
        var(y)
      )
    ],
    apply(f, [const(88)])
  )