Returns number and substrings themselves from the given string

substrings.erl

-module(substrings).
-compile(export_all).


substring(Set, T, Start, LengthOfSubstr) -> 
  S = lists:sublist(T, Start, LengthOfSubstr),
  StringLength = string:len(T),
  if 
    (Start >= StringLength) or (S =:= []) -> sets:to_list(Set);
    %% substring is eql to string || start position + length of substring greater or equal to string's length
    (S =:= T) or (Start + LengthOfSubstr >= StringLength)   -> 
    substring(sets:add_element(S, Set), T, Start + 1, 1); %% shifted to 1 symbol right and start with 1 length of substring
    true 		  -> substring(sets:add_element(S, Set), T, Start, LengthOfSubstr + 1)
  end.

substring(T) -> 
  io:format("~p~n", [substring(sets:new(), T, 1, 1)]).

35> substrings:substring("Hello, World").
["Hell","e","lo, Wo","llo, W","r","Hello, W","llo, Worl","lo,","lo, Wor","o",
"Hello","ello, Worl","l",",",", ",", Wor"," Worl","Worl","el","o, Wo","or",
"Hello, Wo","lo, W","llo, ","lo, Worl","o,","o, Wor",", W","ello,","ello, ",
"ello, Wor"," "," Wor","Wor","He","ell","orl","o, W",", Wo","ello, W","llo",
"lo, ","o, Worl"," W","W","Hello, Worl","ello","Hel","llo, Wo","ello, Wo",
" Wo","Wo","rl","llo,","llo, Wor","lo","o, ","H","Hello,","Hello, ",
"Hello, Wor","ll",", Worl"]