hoist(): simplify only works for all columns or none

[mgirlich]

The .simplify argument doesn't allow to choose which columns should be simplified. One can only choose between all columns (TRUE) or none (FALSE). It would be nicer if one could choose which columns should be simplified.

[hadley]

I think that's reasonable, but it's not clear what the interface should be. A logical vector? A character vector of variables to simplify? A tidyselect specification?

[mgirlich]

Tidyselect specification
+ flexible
+ known to users
- very different from how to specify ptype and transform

Character vector
- feels mostly like an inferior version of the tidyselect specification

(Named) logical vector
+ more similar to ptype and transform
- less flexible than tidyselect

I like the flexibility one gains with the tidyselect specifiation but as ptype and transform do not provide it and tidyselect isn't used in other parts of the functions I'd go with a logical vector.

[hadley]

@DavisVaughan named list solution sounds good.