Expand contents of list columns with bare atomics

[krlmlr]

First three elements only, if there's space.

https://github.com/tidyverse/tibble/issues/892#issuecomment-857808385

Closes tidyverse/tibble#892.

[krlmlr]

And formulas:

library(tidyverse)

tibble::tribble(
  ~var, ~my_func,
  "ABC", ~ tolower(var),
  "abc", ~ toupper(var)
)
#> # A tibble: 2 × 2
#>   var   my_func  
#>   <chr> <list>   
#> 1 ABC   <formula>
#> 2 abc   <formula>

^{Created on 2021-12-25 by the reprex package (v2.0.1)}