How to append 1 element in nested list in Prolog? -

i want append 1 list element in nested list:

predicates     append(li,li,li).  clauses   append([x|y],z,[x|w]):- append(y,z,w).  append([],x,x).   

for example:

append([ [1],[2],[3] ],[4],a) solution: = [ [1],[2],[3],[4] ] 

turbo prolog said: type error.

how can this?

the problem defining domains wrong, , appending 2 different domains (a list of list of integers list of integers).

if want append lists of lists of integers (as seems example) code should be

domains li = integer* lili = li*  predicates   append(lili, lili, lili).  clauses append([x|y],z,[x|w]):- append(y,z,w). append([],x,x). 

and in example second list should list of lists two, yielding:

append([ [1],[2],[3] ],[[4]],a). solution: = [ [1],[2],[3],[4] ] 

note second list [[4]] instead of [4].