The use of this predicate is discouraged in favour of concat_string/2, because the creation of new atoms involves entering them into a dictionary whose garbage collection is relatively expensive.
Success: concat_atom([abc,def],abcdef). concat_atom(["Str1","Str2"],X). X = 'Str1Str2'. concat_atom([the,man," is aged ",20],X). X = 'theman is aged 20'. concat_atom([1,2,3],X) X = '123'. Fail: concat_atom([ab,bc],abc). Error: concat_atom(A,X). (Error 4). concat_atom([abc,D],X). (Error 4). concat_atom(art,X). (Error 5).