Hey guys, i am facing a small problem here, perhaps you could give me any hints with it.

In one of my courses (Program analysis) we are using a language called "The While language" , it is simplified and I think only for education purposes. I am asked to make an abstract syntax out of the concrete one, during it in a language of my choice. This abstract syntax will be used later on to generate the language parser(I think?), Anyway here is the concrete syntax of the language

```
a ::= n | x | A[a] | a1 opa a2 | -a | (a)
b ::= true | false | a1 opr a2 | b1 opb b2 | !b | (b)
S ::= x := a; | skip; | A[a1] := a2; | read x; | read A[a]; | write a; |
S1 S2 | if b then S1 else S2 fi; | while b do S od;
D ::= int x; | int A[n]; | ∊ | D1 D2
P ::= program D S end
opa ∈ {+, -, *, /} int × int → int
opr ∈ {<, >, <=, >=, =, !=} int × int → bool
opb ∈ {&, |} bool × bool → bool
```

Soo, so far so good, I started creating the abstract syntax but I got stucked in a way after talking to the TA. Here is what I have right now

```
public abstract class Exp {}
public abstract class Statement {}
public class Plus extends Exp{
public Exp e1,e2;
public Plus(Exp ae1, Exp ae2){
e1 = ae1;
e2 = ae2;
}
}
public class Substract extends Exp{
public Exp e1,e2;
public Substract(Exp ae1, Exp ae2){
e1 = ae1;
e2 = ae2;
}
}
public class While extends Statement{
public Exp e1;
public Statement s1;
public While(Exp ae1, Statement as1){
e1 = ae1;
s1 = as1;
}
}
public class If extends Statement{
public Exp e1;
public Statement s1;
public Statement s2;
public If(Exp ae1, Statement as1, Statement as2){
e1 = ae1;
s1 = as1;
s2 = as2;
}
}
```

I did a lot of digging on this for minijava to get some ideas of how to do it, anyway, the TA said I was going to the right direction but for the arithmetic expressions I could just define all in 1 class and it is possible to use + ,- ,/ etc instead, which got me a bit confused, would be nice if someone could add stuff on this ...

Another thing is I have to also define Boolean expressions, I'd assume new abstract class BoolExp and then should be similiar to the arithmetic one

Any ideas are more than welcome