Add tasks for all the new languages

Task/Inverted-index/EchoLisp/inverted-index-1.echolisp

@@ -0,0 +1,23 @@
+;; set of input files
+(define FILES {T0.txt T1.txt T2.txt})
+;; store name for permanent inverted index
+(define INVERT "INVERTED-INDEX")
+
+;; get text for each file, and call (action filename text)
+(define (map-files action files)
+	(for ((file files))
+	(file->string action file)))
+	
+;; create store
+(local-make-store INVERT)
+
+; invert-word : word -> set of files
+(define (invert-word word file store)
+	    (local-put-value word
+	    	(make-set  (cons file (local-get-value word store))) store))
+	
+; parse file text and invert each word
+(define (invert-text file text)
+		(writeln 'Inverting file text)
+		(let ((text (text-parse text)))
+		(for ((word text))  (invert-word (string-downcase word) file INVERT))))

Task/Inverted-index/EchoLisp/inverted-index-2.echolisp

@@ -0,0 +1,11 @@
+;; usage : (inverted-search w1 w2 ..)
+(define-syntax-rule (inverted-search w ...)
+			(and-get-invert (quote w )))
+
+;; intersects all sets referenced by words
+;; returns the intersection
+(define (and-get-invert words)
+		(foldl
+			(lambda(word res)
+				 (set-intersect res (local-get-value word  INVERT)))
+			FILES words))

Task/Inverted-index/EchoLisp/inverted-index-3.echolisp

@@ -0,0 +1,9 @@
+(map-files invert-text FILES)
+(inverted-search is it)
+[0]→ { T0.txt T1.txt T2.txt }
+(inverted-search is banana)
+[1]→ { T2.txt }
+(inverted-search is what)
+[2]→ { T0.txt T1.txt }
+(inverted-search boule)
+[3]→ null