Unexpected dimnames when using `reduce` with `cbind` and `rbind`

[hsloot]

I experienced unexpected naming of columns or rows ("out" and "elt") when using reduce(x, cbind) or reduce(x, rbind), resp., on a list x of vectors of the same length. This came up while replacing calls to apply with a combination of array_branch, map, and reduce.

The reason for this seems to be the use of forceAndCall which somehow uses the symbol names to name the arguments in the subsequent call to the function: https://github.com/tidyverse/purrr/blob/5aca9df41452f272fcef792dbc6d584be8be7167/R/reduce.R#L160

I found workarounds with rlang::exec or do.call (see and of the reprex), but I am not familiar enough with lazy evaluation to say whether this is safe to use and does not lead to problems itself.

library(purrr)

matrix(1:9, 3, 3) %>%
  array_branch(2) %>%
  map(~.) %>%
  reduce(cbind)
#>      out elt elt
#> [1,]   1   4   7
#> [2,]   2   5   8
#> [3,]   3   6   9

list(1:3, 4:6, 7:9) %>%
  reduce(cbind)
#>      out elt elt
#> [1,]   1   4   7
#> [2,]   2   5   8
#> [3,]   3   6   9

out <- 1:3
elt <- 4:6
forceAndCall(2, cbind, out, elt)
#>      out elt
#> [1,]   1   4
#> [2,]   2   5
#> [3,]   3   6
rlang::exec(forceAndCall, 2, cbind, !!!list(out, elt))
#>      [,1] [,2]
#> [1,]    1    4
#> [2,]    2    5
#> [3,]    3    6
do.call(forceAndCall, list(2, cbind, out, elt))
#>      [,1] [,2]
#> [1,]    1    4
#> [2,]    2    5
#> [3,]    3    6

^{Created on 2021-05-13 by the reprex package (v2.0.0)}

Session info

sessioninfo::session_info()
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#>  date     2021-05-13                  
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