Function to add multiple inputs

add_multiple.R

library(purrr)

add_vecs <- function(...){
  if(!is.list(...)) stop("must be list input")
  reduce(..., `+`)
}
add_vecs(list(1:5, 1:5, 1:5))
#> [1]  3  6  9 12 15


<sup>Created on 2019-02-15 by the [reprex package](https://reprex.tidyverse.org) (v0.2.1)</sup>

# Apply to dataframe
iris %>% 
  mutate(sum_lengths = select(., contains("Length")) %>% add_vecs())