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Hi, could anyone help me getting some basic concepts straigt? I get what a lattice generally is. But in our case, what are the actual elements of the lattices? Statements? Program states? And what exactly are flow functions? At first I thought the elements of the lattice are program states (meaning ...

I am also still looking for a group.
Anyone?

Hi,
is the exam date in Tucan (Fr, 27. Feb. 2015 11:30-13:30) correct?
Thanks!

Yes, I can access them.

Any updates on the exam date?
Thanks!

Conflicting with what date?

This is what I have for ex06.2 ... This looks wrong to me. I got the following solution before GC based on our implementation of boxes: You are totally right. Thanks for the tipp! So I guess the right solution should look something like this: ## 1. Non-moving GC Env Store ----+----- ----+--------- ...

I am also not sure if there are any special cases. Everthing I did was add a Let case class case class Let(boundId: Symbol, namedExpr: Expr, body: Expr) extends Expr and match it case Let(boundId, namedExpr, body) => { interp(body, env + (boundId -> interp(namedExpr, env, ct)), ct) }

Oh, yes. That seems much simpler
Thanks!

Hi, to get recursion using mutation, I introduced a LetRec expression, which binds the name of the recursive function to a box. The box contains the functions body. For that I also had to change the evaluation of App-expressions. case WithRec(boundId, namedExpr, boundBody) => // create a new box and...

Mr.B hat geschrieben: You could substitute free variables in a first class function definition. This would have the semantics of a closure, right?

Yes!

Regarding ex.06.2 ## 2. Moving-GC Env Store ----+----- ----+--------- x1 | 1 1 | Num(10) x2 | 2 2 | Box(1) x3 | 3 3 | Box(2) res | 8 8 | Box(3) Shouldn't be the adress of Box(3) be 4? And then ofcourse the pointer of res 4 as well? Yes, I think so, too. After GC: Env Store ----+----- ----+--------- ...

I think the idea was that code which has side effects evaluates differently in substitution vs environment. Think of a "let" which binds an expression which makes your programm terminate to a variable which is never used. If you have (lazy) substitution, it will not error out because the bound expr...

Jep, I'm with Mr.B here.
So I guess no one else has an idea for something that I cannot implement using substitution that I could implement using environments (without a store)?

Hi, # Exercise 03 ## Task 1: Immediate substitution vs deferred substitution For the language F1WAE, we introduced environments as an alternative for substitutions. ### 1. Why did we do this? Increase efficiency: we don't have to traverse the whole program (especially unvisited branches) for substi...