prompt claude

Finally, implement for #lists: `TypeList`, `List`, `ConsList`, `Head`, `Tail`, `IsEmpty`
**Lists**

```stella
extend with #lists;
Copy
```

A list is a homogenous collection of elements of an arbitrary length. Its type is written as `[Type]`, and it is constructed using either the `cons` expression which accepts the head and the tail to be linked, or using the `[expr1, expr2, ...]` syntax. The first element of the list can be accessed using `List::head`, the remaining elements (as a list) using `List::tail`, and you can check if it's empty using `List::isempty`.

```stella
language core;

extend with #lists;
extend with #multiparameter-functions;

fn nonempty(list : [Nat]) -> Bool {
  return if List::isempty(list) then true else false
}

fn first_or_default(list : [Nat], default : Nat) -> Nat {
  return if nonempty(list) then List::head(list) else default
}

fn main(default : Nat) -> Nat {
  return first_or_default([], default)
}
```


```
// File generated by the BNF Converter (bnfc 2.9.5).

package org.syntax.stella.Absyn;

public class TypeList  extends Type {
  public final Type type_;
  public int line_num, col_num, offset;
  public TypeList(Type p1) { type_ = p1; }

  public  R accept(org.syntax.stella.Absyn.Type.Visitor v, A arg) { return v.visit(this, arg); }

  public boolean equals(java.lang.Object o) {
    if (this == o) return true;
    if (o instanceof org.syntax.stella.Absyn.TypeList) {
      org.syntax.stella.Absyn.TypeList x = (org.syntax.stella.Absyn.TypeList)o;
      return this.type_.equals(x.type_);
    }
    return false;
  }

  public int hashCode() {
    return this.type_.hashCode();
  }


}
```



```
// File generated by the BNF Converter (bnfc 2.9.5).

package org.syntax.stella.Absyn;

public class List  extends Expr {
  public final ListExpr listexpr_;
  public int line_num, col_num, offset;
  public List(ListExpr p1) { listexpr_ = p1; }

  public  R accept(org.syntax.stella.Absyn.Expr.Visitor v, A arg) { return v.visit(this, arg); }

  public boolean equals(java.lang.Object o) {
    if (this == o) return true;
    if (o instanceof org.syntax.stella.Absyn.List) {
      org.syntax.stella.Absyn.List x = (org.syntax.stella.Absyn.List)o;
      return this.listexpr_.equals(x.listexpr_);
    }
    return false;
  }

  public int hashCode() {
    return this.listexpr_.hashCode();
  }


}
```



```
// File generated by the BNF Converter (bnfc 2.9.5).

package org.syntax.stella.Absyn;

public class ConsList  extends Expr {
  public final Expr expr_1, expr_2;
  public int line_num, col_num, offset;
  public ConsList(Expr p1, Expr p2) { expr_1 = p1; expr_2 = p2; }

  public  R accept(org.syntax.stella.Absyn.Expr.Visitor v, A arg) { return v.visit(this, arg); }

  public boolean equals(java.lang.Object o) {
    if (this == o) return true;
    if (o instanceof org.syntax.stella.Absyn.ConsList) {
      org.syntax.stella.Absyn.ConsList x = (org.syntax.stella.Absyn.ConsList)o;
      return this.expr_1.equals(x.expr_1) && this.expr_2.equals(x.expr_2);
    }
    return false;
  }

  public int hashCode() {
    return 37*(this.expr_1.hashCode())+this.expr_2.hashCode();
  }


}
```



```
// File generated by the BNF Converter (bnfc 2.9.5).

package org.syntax.stella.Absyn;

public class Head  extends Expr {
  public final Expr expr_;
  public int line_num, col_num, offset;
  public Head(Expr p1) { expr_ = p1; }

  public  R accept(org.syntax.stella.Absyn.Expr.Visitor v, A arg) { return v.visit(this, arg); }

  public boolean equals(java.lang.Object o) {
    if (this == o) return true;
    if (o instanceof org.syntax.stella.Absyn.Head) {
      org.syntax.stella.Absyn.Head x = (org.syntax.stella.Absyn.Head)o;
      return this.expr_.equals(x.expr_);
    }
    return false;
  }

  public int hashCode() {
    return this.expr_.hashCode();
  }


}
```



```
// File generated by the BNF Converter (bnfc 2.9.5).

package org.syntax.stella.Absyn;

public class Tail  extends Expr {
  public final Expr expr_;
  public int line_num, col_num, offset;
  public Tail(Expr p1) { expr_ = p1; }

  public  R accept(org.syntax.stella.Absyn.Expr.Visitor v, A arg) { return v.visit(this, arg); }

  public boolean equals(java.lang.Object o) {
    if (this == o) return true;
    if (o instanceof org.syntax.stella.Absyn.Tail) {
      org.syntax.stella.Absyn.Tail x = (org.syntax.stella.Absyn.Tail)o;
      return this.expr_.equals(x.expr_);
    }
    return false;
  }

  public int hashCode() {
    return this.expr_.hashCode();
  }


}
```



```
// File generated by the BNF Converter (bnfc 2.9.5).

package org.syntax.stella.Absyn;

public class IsEmpty  extends Expr {
  public final Expr expr_;
  public int line_num, col_num, offset;
  public IsEmpty(Expr p1) { expr_ = p1; }

  public  R accept(org.syntax.stella.Absyn.Expr.Visitor v, A arg) { return v.visit(this, arg); }

  public boolean equals(java.lang.Object o) {
    if (this == o) return true;
    if (o instanceof org.syntax.stella.Absyn.IsEmpty) {
      org.syntax.stella.Absyn.IsEmpty x = (org.syntax.stella.Absyn.IsEmpty)o;
      return this.expr_.equals(x.expr_);
    }
    return false;
  }

  public int hashCode() {
    return this.expr_.hashCode();
  }


}
```