Initial data commit

Task/S-expressions/Factor/s-expressions.factor

@@ -0,0 +1,27 @@
+USING: formatting kernel math.parser multiline peg peg.ebnf
+regexp sequences prettyprint words ;
+IN: rosetta-code.s-expressions
+
+STRING: input
+((data "quoted data" 123 4.5)
+ (data (!@# (4.5) "(more" "data)")))
+;
+
+EBNF: sexp>seq [=[
+  ws     = [\n\t\r ]* => [[ drop ignore ]]
+  digits = [0-9]+
+  number = digits => [[ string>number ]]
+  float  = digits:a "." digits:b => [[ a b "." glue string>number ]]
+  string = '"'~ [^"]* '"'~ => [[ "" like ]]
+  symbol = [!#-'*-~]+ => [[ "" like <uninterned-word> ]]
+  object = ws ( float | number | string | symbol ) ws
+  sexp   = ws "("~ ( object | sexp )* ")"~ ws => [[ { } like ]]
+]=]
+
+: seq>sexp ( seq -- str )
+    unparse R/ {\s+/ "(" R/ \s+}/ ")" [ re-replace ] 2bi@ ;
+
+input [ "Input:\n%s\n\n" printf ] [
+    sexp>seq dup seq>sexp
+    "Native:\n%u\n\nRound trip:\n%s\n" printf
+] bi