r:tidyverse: How to change column data type using pipes with least typing

With typing reference to the column just once - the compliant answer is

mtcars %<>% mutate_at(6, as.integer)

To refer to column by name, solution with one redundant typing of column name is

mtcars %<>% mutate(qsec = as.integer(qsec))

NOTE:credit goes to commenting users above

This solution is probably the shortest:

mtcars$qsec %<>% as.integer

The trick is to perform the cast operation directly on the column > no need for mutate() any more.