ML-style (* nested (* comments *) *)

extra/nested-comments/nested-comments.factor

@@ -0,0 +1,20 @@
+! by blei on #concatenative
+USING: kernel sequences math locals make multiline ;
+IN: nested-comments
+
+:: (subsequences-at) ( sseq seq n -- )
+    sseq seq n start*
+    [ dup , sseq length + [ sseq seq ] dip (subsequences-at) ]
+    when* ;
+
+: subsequences-at ( sseq seq -- indices )
+    [ 0 (subsequences-at) ] { } make ;
+
+: count-subsequences ( sseq seq -- i )
+    subsequences-at length ;
+
+: parse-all-(* ( parsed-vector left-to-parse -- parsed-vector )
+    1 - "*)" parse-multiline-string [ "(*" ] dip
+    count-subsequences + dup 0 > [ parse-all-(* ] [ drop ] if ;
+
+SYNTAX: (* 1 parse-all-(* ;