pair a b ::= Pair a b;

list a ::= Nil | Cons a (list a);

{ What you get after expanding out type synonyms }
{
cExprP a            
      ::= EVar name 
          | ENum num
          | EConstr name 
          | EAp (cExprP a) (cExprP a)
          | ELet    
               isRec 
               (list (pair a (cExprP a)))
               (cExprP a)
          | ECase   
               (cExprP a) 
               (list (pair (list char) (pair (list a) (cExprP a))))
          | ELam    
               (list a)
               (cExprP a)
}

cExprP t1 t2 t3 t4 t5 t6 t7
      ::= EVar t1 
          | ENum t2
          | EConstr t3 
          | EAp (cExprP t1 t2 t3 t4 t5 t6 t7) (cExprP t1 t2 t3 t4 t5 t6 t7)
          | ELet    
               t4
               t5
               (cExprP t1 t2 t3 t4 t5 t6 t7)
          | ECase   
               (cExprP t1 t2 t3 t4 t5 t6 t7) 
               t6
          | ELam    
               t7
               (cExprP t1 t2 t3 t4 t5 t6 t7)

; ;; 

append l1 l2 = case l1 of
   Nil -> l2;
   Cons x xs -> Cons x (append xs l2)
   end;

getBs dl =
   case dl of
      Nil -> Nil;
      Cons bi bis -> Cons (case bi of Pair naam rhs -> naam end) (getBs bis)
   end;

concat ll =
   case ll of 
      Nil -> Nil;
      Cons lx lxx -> append lx (concat lxx)
   end;

allBinders e = case e of
   EVar v -> Nil;
   ENum n -> Nil;
   EConstr c -> Nil;
   EAp e1 e2 -> append (allBinders e1) (allBinders e2);
   ELet rf dl e12 -> Cons rf (append (concat (getBs dl)) (allBinders e12));
   ECase sw alts -> Nil;
   ELam vs e11 -> allBinders e11 
   end;