Check your code

Goal: find the mistakes in an R project that R reports only when a line runs, then format the project. There is nothing to configure and nothing to annotate, and the code keeps running on GNU R. Install ry first.

Find mistakes

Take a package whose R/discount.R has a typo:

apply_discount <- function(price, rate) {
  price * ratee
}

Run ry check anywhere in the project. It works the same in a folder of scripts with no DESCRIPTION:

$ ry check
unresolved

  ! I could not resolve `ratee` in this package, its imports, or builtins. Did you mean `rate`?
   --[R/discount.R:2:11]
 1 | apply_discount <- function(price, rate) {
 2 |   price * ratee
   |           ^^^^^
 3 | }
  help: Change to `rate` (`ry check --fix --unsafe-fixes` applies it)

1 problem in 1 file
1 fixable with `ry check --fix --unsafe-fixes`

A finding starts with its code (unresolved), then ! for a warning or x for an error. The exit status is 1 when anything is found. Fix and silence covers the help: line.

ry resolves every name by R’s scoping rules, so it knows what each file can see:

File	Sees
R/*.R	one package namespace, plus library() calls and the imports in DESCRIPTION and NAMESPACE
a script	its own definitions, the package’s, and every file it source()s by a literal path
tests/testthat/*.R	the package, plus helper-*.R and setup-*.R
.Rmd, .qmd, .Rnw	its R chunks in order, as one script

The same analysis reports an assignment nothing reads, a top-level name defined twice, pkg::name where pkg does not export name, and a NAMESPACE entry that does not exist. Inside dplyr verbs, data.table’s [ and with(), a bare name is a column, so it is not reported.

After library(pkg) of a package ry has no stub for, any bare name might be one of its exports, so ry stops reporting unresolved names in the whole project. A stub turns the check back on.

Syntax errors

For this code, R says unexpected symbol and stops. ry names what is missing and keeps analyzing the rest of the file:

config <- list(
  title = "Revenue"
  subtitle = "by quarter"
)

syntax-error

  x missing `,` between these arguments
   --[R/config.R:2:20]
 1 | config <- list(
 2 |   title = "Revenue"
   |                    ^

Lints

Eleven lints are on by default. Three of them flag style that hides bugs, here in R/rates.R:

total = 2L
flag <- T
x <- c(1, 2, )
print(totl)

assignment-operator

  ! Use <-, not =, for assignment

boolean-shorthand

  ! Use TRUE, not T, for Boolean values

trailing-comma

  ! Unexpected comma after last argument

The other eight flag code that reads right but does something else:

Code	Flags	Why
equals-na	x == NA	always NA
vector-logic	& or | in an if	evaluates both sides
length-sequence	1:length(x)	counts down to 0 when x is empty
class-equals	class(x) == "data.frame"	misses a tibble
length-test	length(x == 0)	measures the comparison
unreachable-code	code after return() or stop()	never runs
sprintf-arguments	sprintf("%s %s", a)	wrong number of values
object-system	an S4, R6 or Reference Class definition	records and tags are checked

Opt-in style lints, such as single-quotes and redundant-return, are listed in Diagnostic codes.

Fix and silence

On R/rates.R above, ry check --fix applies the safe fixes (= to <-, T to TRUE, the trailing comma) and reports what is left. A spelling suggestion is a guess, so it needs --unsafe-fixes as well:

$ ry check --fix
unresolved

  ! I could not resolve `totl` in this package, its imports, or builtins. Did you mean `total`?
   --[R/rates.R:4:7]
 3 | x <- c(1, 2)
 4 | print(totl)
   |       ^^^^
  help: Change to `total` (`ry check --fix --unsafe-fixes` applies it)

applied 3 fixes
1 problem in 1 file
1 fixable with `ry check --fix --unsafe-fixes`

To accept one finding, name its code in a comment on the line or the line above:

y = 3L  # ry: allow(assignment-operator)

lintr’s # nolint comments work too. To turn a check off for the project, set it in ry.toml.

Format

ry fmt formats every file in place:

x<-c(1,2,3)
if(x>1){y<-2}
for (i in 1:3) print(i)

x <- c(1, 2, 3)
if (x > 1) { y <- 2 }
for (i in 1:3) {
  print(i)
}

Every loop body gets braces. There is no column limit: a call you wrote on one line stays on one line, and a call you broke across lines gets one argument per line. ry fmt --range 2-3 FILE formats only those lines. Formatting rules has every rule.

In CI

ry check        # exit status 1 on any finding
ry fmt --check  # exit status 1 if a file is not formatted

Pin the ry version in CI, because a newer release can report findings an older one did not. ry check --output json writes one JSON object per finding (CLI).

In the editor

The language server shows the same findings as you type, with hover, completion, go to definition, references, rename and quick fixes for the same fixes. Installation sets it up.

Next: type your code.