Today’s Erlang Thursday is on string:join/2.

string:join/2 takes a list of strings as its first argument, and a string separator used to join the strings together into a single string.

91> string:join(["a", "b", "c"], "").
"abc"
92> string:join(["a", "b", "c"], "-").
"a-b-c"

The separator string can be a string of any length, and doesn’t just have to be a single character.

93> string:join(["a", "b", "c"], "___").
"a___b___c"
94> string:join(["a", "b", "c"], " ").  
"a b c"

And as with any string, a list of characters, or even integers, can be used as the separator string.

string:join(["a", "b", "c"], [$A]).
# "aAbAc"
string:join(["a", "b", "c"], [52]).
# "a4b4c"

–Proctor