[WIP] Provide ff_string:join/1 w/ no delim

apps/ff_core/src/ff_string.erl

@@ -3,19 +3,26 @@
 
 -module(ff_string).
 
+-export([join/1]).
 -export([join/2]).
 
 %%
 
--spec join(Delim, [Fragment]) -> binary() when
+-type fragment() ::
+    iodata() |
+    char()   |
+    atom()   |
+    number() .
+
+-spec join([fragment()]) -> binary().
+
+join(Fragments) ->
+    join(<<>>, Fragments).
+
+-spec join(Delim, [fragment()]) -> binary() when
     Delim ::
         char()   |
-        iodata() ,
-    Fragment ::
-        iodata() |
-        char()   |
-        atom()   |
-        number() .
+        iodata() .
 
 join(Delim, Fragments) ->
     genlib_string:join(Delim, lists:map(fun genlib:to_binary/1, Fragments)).