Taken from The Power of Prolog by Markus Triska

It's recommended to set the flag to write lists of characters as strings:

:- set_prolog_flag(double_quotes, chars).

See also

- https://www.metalevel.at/prolog/dcg

 seq(-List)// is det

seq(+List)// is det

Describes a sequence of elements.

?- phrase(("Hello, ",seq(Cs),"!"), "Hello, all!").
Cs = "all" ;
false.

 seqq(-List)// is det

seqq(+List)// is det

Describes a sequence of sequences.

?- phrase(seqq(["ab","cd","ef"]), Ls).
   Ls = "abcdef".

 ...// is det

Describes "any sequence at all"

?- phrase((...,"you",...,"!"), "Hello, you all!").
   true ;
   false.