Use the force(x), Vince

purrr_force.R

library(purrr)

foo <- function(x) {
  function(y) {
    y + x
  }
}

args <- list(1, 2)
foos_map <- map(args, foo)
foos_lapply <- lapply(args, foo)

foos_map[[1]](1)
#> [1] 3
foos_lapply[[1]](1)
#> [1] 2

foos_map[[1]](2)
#> [1] 4
foos_lapply[[1]](2)
#> [1] 3

get("x", envir=environment(foos_map[[1]]))
#> [1] 2
get("x", envir=environment(foos_map[[2]]))
#> [1] 2

get("x", envir=environment(foos_lapply[[1]]))
#> [1] 1
get("x", envir=environment(foos_lapply[[2]]))
#> [1] 2

## NOTE: force(x) ensures evaluation of x in that environment
## probably equivalently, just x

foo2 <- function(x) {
  force(x) ## IMPORTANT!
  function(y) {
    y + x
  }
}

args <- list(1, 2)
foos_map2 <- map(args, foo2)
foos_lapply2 <- lapply(args, foo2)

foos_map2[[1]](1)
#> [1] 2
foos_lapply2[[1]](1)
#> [1] 2

foos_map2[[1]](2)
#> [1] 3
foos_lapply2[[1]](2)
#> [1] 3

get("x", envir=environment(foos_map2[[1]]))
#> [1] 1
get("x", envir=environment(foos_map2[[2]]))
#> [1] 2

get("x", envir=environment(foos_lapply2[[1]]))
#> [1] 1
get("x", envir=environment(foos_lapply2[[2]]))
#> [1] 2