Weird behavior with flatten?

[kevmoo]

I'd expect this to pass (copy-paste into core_test.dart).

Thoughts?

test('foo', () {
  var letterLine = letter().plus().flatten().seq(Token.newlineParser())
      .pick(0);

  var parser = digit().plus().seq(letterLine).flatten();
  expectSuccess(parser, '123abc\n', '123abc');
});

[kevmoo]

Perhaps I'm confused by the behavior of flatten.

In the above code, if you remove flatten() at the end of var parser = one gets

[[1, 2, 3], abc]

The newline was consumed, but it was excluded by a pick.

My naive view would be that flatten would take whatever it's given and, well, flatten the strings.

The fact that it uses the starting and ending parse positions to get a substring is weird...at least to me.

...but I'm new to this.

[renggli]

The following parser makes your test pass:

var parser = digit().plus()
    .seq(letter().plus())
    .flatten()
      .seq(Token.newlineParser())
      .pick(0);

Regarding the behavior of flatten please check the docs and let me know if something is unclear. To process and join the strings you cold use map and join along the following snippet:

digit().plus().map((List list) => list.join())