New operators not exported by Control.Lens.Operators

[endgame]

These operators, introduced in lens-5.3, are not re-exported through Control.Lens.Operators:

• (<>:~): prepend an element to the front via (<>).
• (<<>:~): append an element to the back prepend an element to the front via (<>).
• (<|~): cons an element to the front via (<|).
• (<<|~): cons an element to the front via (<|) and return the result.
• (|>~): snoc an element to the back via (|>).
• (<|>~): snoc an element to the back via (|>) and return the result.

(<<>:~) appears misdocumented in the changelog: it is actually left-side <> and-return-result

Should these lenses also have << variants which return the old value?

Ping @ncaq

[RyanGlScott]

Yes, I think we should re-export these from Control.Lens.Operators as well.

(<<>:~) appears misdocumented in the changelog: it is actually left-side <> and-return-result

Sorry about that! I wrote the CHANGELOG after #1058 had landed, so any errors in the CHANGELOG are purely my fault. @ncaq, would you be willing to double-check what I wrote and fix any inaccuracies?

Should these lenses also have << variants which return the old value?

Thoughts, @ncaq?

[ncaq]

I think it is a good policy to export.

[RyanGlScott]

OK. Regarding the CHANGELOG mistake, I think I was confused by the Haddocks for (<<>:~):

lens/src/Control/Lens/Lens.hs

Lines 1195 to 1201 in 1ce86ea

	-- | ('<>') a 'Semigroup' value onto the end of the target of a 'Lens' and
	-- return the result.
	-- However, unlike '<<>~', it is prepend to the head side.
	--
	-- When you do not need the result of the operation, ('Control.Lens.Setter.<>:~') is more flexible.
	(<<>:~) :: Semigroup m => LensLike ((,)m) s t m m -> m -> s -> (m, t)
	l <<>:~ m = l <%~ (m <>)

The Haddocks talk about appending an element to the end, but the implementation prepends to the front instead. As such, I think we need to correct both the Haddocks and the CHANGELOG.

[RyanGlScott]

I've submitted a fix in #1068.

[ncaq]

I copied and pasted the basic part thinking it was basically the same and unlike it, prepend to the head side...
I should have checked the basic part properly.
I made a mistake because I am not good at English.
Thank you for your time and effort.

[RyanGlScott]

No problem at all, @ncaq. Thank you for your contribution!

[endgame]

Thank you for your time and effort.

And thank you for yours.