Using tryCatch() from R together with reduce() from Purrr

output.txt

> source("tryWithError.R")
List of 7
 $ :List of 4
  ..$ value  : num 1
  ..$ success: logi TRUE
  ..$ errors : NULL
  ..$ data   : int 1
 $ :List of 4
  ..$ value  : num 3
  ..$ success: logi TRUE
  ..$ errors : NULL
  ..$ data   : int [1:3] 1 2 3
 $ :List of 4
  ..$ value  : num 5
  ..$ success: logi TRUE
  ..$ errors : NULL
  ..$ data   : int [1:5] 1 2 3 4 5
 $ :List of 4
  ..$ value  : num 7
  ..$ success: logi TRUE
  ..$ errors : NULL
  ..$ data   : int [1:7] 1 2 3 4 5 6 7
 $ :List of 4
  ..$ value  : num 9
  ..$ success: logi TRUE
  ..$ errors : NULL
  ..$ data   : int [1:9] 1 2 3 4 5 6 7 8 9
 $ :List of 4
  ..$ value  : num 15
  ..$ success: logi FALSE
  ..$ errors : chr "Failed toTry(15), error: 15 is greater than twelve"
  ..$ data   : list()
 $ :List of 4
  ..$ value  : num 21
  ..$ success: logi FALSE
  ..$ errors : chr "Failed toTry(21), error: 21 is greater than twelve"
  ..$ data   : list()
List of 2
 $ data  : int [1:25] 1 1 2 3 1 2 3 4 5 1 ...
 $ errors: chr [1:4] "There was trouble with value 15" "Failed toTry(15), error: 15 is greater than twelve" "There was trouble with value 21" "Failed toTry(21), error: 21 is greater than twelve"
>

tryWithError.R

require(purrr)

toTry <- function(value) {
  if (12 < value) {
    stop(sprintf("%d is greater than twelve", value))
  }
  seq(1, value)
}

tryWithError <- function(value) {
  errors <- c()
  success <- TRUE
  onError <- function(e) {
    errors <<- c(errors, sprintf("Failed toTry(%d), error: %s",
      value, e$message))
    success <<- FALSE
    list()
  }
  data <- tryCatch(toTry(value), error=onError, warning=onError)
  list(value=value, success=success, errors=errors, data=data)
}

reduction <- function(trackingList, value) {
  result = tryWithError(value)
  if (result$success) {
    trackingList$data <- if (is.null(trackingList$data)) {
      result$data
    } else {
      c(trackingList$data, result$data)
    }
  } else {
    trackingList$errors <- c(
      trackingList$errors,
      sprintf("There was trouble with value %d", value),
      result$errors
    )
  }
  trackingList
}

values <- c(1, 3, 5, 7, 9, 15, 21)

testTryWithL <- function() {
  str(lapply(values, tryWithError))
}

testTryWithReduce <- function() {
  str(reduce(values, reduction, .init=list()))
}

testTryWithL()
testTryWithReduce()