Merge pull request #60 from upsilon/fix-selectmany

Fixed #58: An empty list terminates flatMap (selectMany) sequence.

v0.2.3 release

0.2.2 release

0.2.1 release

v0.2.0 release

Fixed unfold rewind bug

v0.1.3 release

0.1.2 release

Fixed few PhpStorm warning

Modified README.*.md