Turn a sentence into a dictionary For this challenge, you will be given a long string as an input. With this string, you must create a dictionary.
Details:
This dictionary will contain all the words from the string - a word being any sequence of letters surrounded by non-letter characters (ASCII). Letter case of the entries of the dictionary should always be consistent (i.e. all lower case or all upper case, or only the first letter of each word is capitalised). The dictionary can be a list, array, or any other type so long as the words are distinct from each other. Finally, as this is a dictionary, the words must be in alphabetical order, and there may not be any duplicates.
You can assume no contractions will be used (the input will never contain it's, there's, etc.), and that there will always be at least one word
Some examples:
&quot;this is an eXaMpLe of an Input&quot; -&gt; [&quot;an&quot;,&quot;example&quot;,&quot;input&quot;,&quot;is&quot;,&quot;of&quot;,&quot;this&quot;]
&quot;Here is another example of an input, this time with Punctuation!&quot; -&gt; [&quot;an&quot;,&quot;another&quot;,&quot;example&quot;,&quot;here&quot;,&quot;input&quot;,&quot;is&quot;,&quot;of&quot;,&quot;punctuation&quot;,&quot;this&quot;,&quot;time&quot;,&quot;with&quot;]
&quot;290(&amp;79832aAa(*&amp; *79 --=BBBb)bbBb ( x )*d -cxaAa_&quot; -&gt; [&quot;aaa&quot;,&quot;bbbb&quot;,&quot;cxaaa&quot;,&quot;d&quot;,&quot;x&quot;]

Scoring
Shortest code wins
JavaScript (ES6),  57  51 bytes
Returns a Set of words in lower case.
NB: In JS, the elements of a Set are guaranteed to appear in insertion order. In this case, this  is the order defined in the sorted array the Set is built from.

s=&gt;new Set(s.toLowerCase().match(/[a-z]+/g).sort())

Try it online!