-- returns a list where all elements are replaced by the first element
multfirst :: [a] -> [a]
multfirst [] = []
multfirst [a] = [a]
multfirst [a,b] = [a,a]
multfirst [a,b,c] = [a,a,a]
multfirst [a,b,c,d] = [a,a,a,a]