coalesce

Flag if (is.null(x)) y else x (and its mirror if (!is.null(x)) x else y), which is the null-coalescing x %||% y—shorter, and it evaluates x once instead of twice.

The rule fires only when is.null resolves to base R; a local redefinition is left alone. The fix is unsafe: %||% needs R >= 4.4 (or rlang), and collapsing the two evaluations of x changes behavior when x has side effects.

This rule is enabled by default.

Falling back to a default when a value is NULL:

y <- if (is.null(x)) default else x

warning: coalesce
 --> example.R:1:6
  |
1 | y <- if (is.null(x)) default else x
  |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `if (is.null(x)) y else x` is the null-coalescing `x %||% y`
  = help: Use `x %||% y`.