-- Haskell function to append two lists
app [] bs     = bs
app (a:as) bs = a:res where
    res = app as bs
    
% Prolog function to append two lists
app( [], Bs, Bs ).
app( [A|As], Bs, [A|Res] ) :-
    app( As, Bs, Res ).
    

-- Haskell function to reverse a list
rev lst = revAcc lst
revAcc []     rs = rs
revAcc (a:as) rs = revAcc as (a:rs)

% Prolog function to reverse a list
rev( Lst, Res ) :- revAcc( Lst, [], Res ).
revAcc( [], Bs, Bs ).
revAcc( [A|As], Rs, Res ) :- revAcc( As, [A|Rs], Res ).