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Switch Between Explicit function() and Implicit \() Syntax

Source: R/16_convert_func_syntax.R
convert_func_syntax.Rd

Converts all function definitions in an R file between the explicit function() syntax and the R 4.1+ concise lambda \() syntax. Handles strings and comments correctly, and supports nested function definitions via iterative passes.

Usage

convert_func_syntax(
  path = NULL,
  direction = c("to_lambda", "to_explicit"),
  ...
)

Arguments

path

A character string specifying the path to the R file to modify. If NULL and RStudio is available, the currently active document path is used.

direction

Conversion direction. One of:

  • "to_lambda": convert function(...) to \(...)

  • "to_explicit": convert \(...) to function(...)

...

Additional arguments. Currently unused and must be empty.

Value

Invisibly returns the path to the modified file.

Details

The conversion correctly handles strings, comments, and nested parentheses in default argument values (e.g., function(x = foo(y))).

Nested function definitions (e.g., function(x, f = function(y) ...)) are converted in multiple iterative passes, so all nesting levels are reached.

Examples

# \donttest{
temp <- tempfile(fileext = ".R")
writeLines("add_one <- function(x) x + 1", temp)
convert_func_syntax(temp, direction = "to_lambda")
#> ✔ Converted function definitions in /tmp/RtmpAM3FIu/file1b243cdb145a.R to "to_lambda"
readLines(temp)
#> [1] "add_one <- \\(x) x + 1"
# "add_one <- \(x) x + 1"
convert_func_syntax(temp, direction = "to_explicit")
#> ✔ Converted function definitions in /tmp/RtmpAM3FIu/file1b243cdb145a.R to "to_explicit"
readLines(temp)
#> [1] "add_one <- function(x) x + 1"
# "add_one <- function(x) x + 1"
# }