output: rmarkdown::github_document: pandoc_args: ["--wrap=none"]

lintr

{lintr} provides static code analysis for R. It checks for adherence to a given style, identifying syntax errors and possible semantic issues, then reports them to you so you can take action.

For example, given a file bad.R with the following contents:

my_func = function(x){
    if(x > 0){
        print("Positive")
    }
    else {
        print("Not positive")
    }
    return(T)
}

Running lintr::lint() on this file would produce the following output:

lintr::lint("bad.R")

bad.R:1:9: style: [assignment_linter] Use one of <-, <<- for assignment, not =.
my_func = function(x){
        ^
bad.R:1:22: style: [brace_linter] There should be a space before an opening curly brace.
my_func = function(x){
                     ^
bad.R:1:22: style: [paren_body_linter] Put a space between a right parenthesis and a body expression.
my_func = function(x){
                     ^
bad.R:2:4: style: [indentation_linter] Indentation should be 2 spaces but is 4 spaces.
    if(x > 0){
  ~^
bad.R:2:7: style: [spaces_left_parentheses_linter] Place a space before left parenthesis, except in a function call.
    if(x > 0){
      ^
bad.R:2:14: style: [brace_linter] There should be a space before an opening curly brace.
    if(x > 0){
             ^
bad.R:2:14: style: [paren_body_linter] Put a space between a right parenthesis and a body expression.
    if(x > 0){
             ^
bad.R:3:8: style: [indentation_linter] Indentation should be 4 spaces but is 8 spaces.
        print("Positive")
    ~~~^
bad.R:4:4: style: [indentation_linter] Indentation should be 2 spaces but is 4 spaces.
    }
  ~^
bad.R:5:5: style: [brace_linter] `else` should come on the same line as the previous `}`.
    else {
    ^~~~
bad.R:6:8: style: [indentation_linter] Indentation should be 4 spaces but is 8 spaces.
        print("Not positive")
    ~~~^
bad.R:7:4: style: [indentation_linter] Indentation should be 2 spaces but is 4 spaces.
    }
  ~^
bad.R:8:5: style: [return_linter] Use implicit return behavior; explicit return() is not needed.
    return(T)
    ^~~~~~
bad.R:8:13: style: [T_and_F_symbol_linter] Use TRUE instead of the symbol T.
    return(T)
           ~^
bad.R:10:1: style: [trailing_blank_lines_linter] Remove trailing blank lines.

^

{lintr} is complementary to the {styler} package which automatically restyles code, eliminating some of the problems that {lintr} can detect.

Installation

Install the stable version from CRAN:

install.packages("lintr")

Or the development version from GitHub:

# install.packages("remotes")
remotes::install_github("r-lib/lintr")

Usage

And then you can create a configuration file and run selected linters:

lintr::use_lintr(type = "tidyverse")

# in a project:
lintr::lint_dir()

# in a package:
lintr::lint_package()

To see a list of linters included for each configuration:

# tidyverse (default)
names(lintr::linters_with_defaults())

# full
names(lintr::all_linters())

Setting up GitHub Actions

{usethis} provides helper functions to generate lint workflows for GitHub Actions:

# in a project:
usethis::use_github_action("lint-project")

# in a package:
usethis::use_github_action("lint")

You can also run lintr during continuous integration or within your IDE or text editor. See vignette("continuous-integration") and vignette("editors") for more details.

Without further configuration, this will run the default linters. See vignette("lintr") to learn how to modify these defaults.

Code of Conduct

Please note that the lintr project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.