outer join the wrong way around ...

[maxigit]

Describe the bug
leftJoin do a rightJoin and vice versa. Trying the examples in the documentation for left and right gives the opposite result. D.leftJoin ["key"] df other returns

-----------------
 key  |  A  |  B
------|-----|----
 Text | Text| Text
------|-----|----
 K0   | A0  | B0
 K1   | A1  | B1

where rightJoin returns

------------------------
 key  |  A  |     B
------|-----|----------
 Text | Text| Maybe Text
------|-----|----------
 K0   | A0  | Just [B0](https://hackage-content.haskell.org/package/dataframe-0.4.1.0/docs/B0.html)
 K1   | A1  | Just [B1](https://hackage-content.haskell.org/package/dataframe-0.4.1.0/docs/B1.html)
 K2   | A2  | Just [B2](https://hackage-content.haskell.org/package/dataframe-0.4.1.0/docs/B2.html)
 K3   | A3  | Nothing

To Reproduce
Try the example in the documentation.

Expected behavior
leftJoin performing a left join and rightJoin performing a right join, unless this has been done in purpose to allow piping and it is intended to be used as df |> D.leftJoin ["key"] other.
In that case, the documentation is incorrect.

Desktop (please complete the following information):
I've been using the ihaskell-dataframe git repo. It looks behind a bit, so maybe the problem has been fixed since.

[daikonradish]

My opinion is that the documentation is wrong since in general the style in this library is to pipe. Which violates your expectation more @maxigit?

[maxigit]

I expect leftJoin a b to use a as the left bit, so the actual documentation behavior ...