library_call

Added in 0.7.0

What it does

Reports library() calls that are not grouped at the top of the script.

Why is this bad?

Scripts where library() calls are scattered between the code are hard to read: a reader cannot tell at a glance which packages the script needs. This rule has several special cases:

an if statement that only contains library() calls is considered equivalent to a simple library() call;
similarly, suppressMessages() and suppressPackageStartupMessages() containing library() calls are considered equivalent to a simple library() call;
options() and Sys.setenv() at the top of the script stay there. Jarl will not move library() calls above these functions.
this rule is skipped in R Markdown and Quarto documents, where it is more common to have library() calls in various chunks.

Comments located on the same line as the library() call are moved with it, but comments preceding it are not.

This rule has an unsafe fix that moves library() calls towards the top. This is unsafe because code that would initially run before some library() calls would run after and therefore could be affected by new namespace conflicts.

This rule is disabled by default.

Example

library(dplyr)
x <- 1
library(purrr)
y <- 2
library(data.table)

Use instead:

library(dplyr)
library(purrr)
library(data.table)
x <- 1
y <- 2