Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

# Basic function definition
greet <- function(name, greeting = "Hello") {
    paste(greeting, name)
}
greet("Alice")             # "Hello Alice"
greet("Bob", "Hi")         # "Hi Bob"
greet(greeting = "Hey", name = "Carol")  # named args, any order

# Last-expression return (no explicit return() needed)
square <- function(x) x ^ 2
square(7)   # 49

# Explicit return for early exit
safe_log <- function(x) {
    if (x <= 0) return(NA)
    log(x)
}
safe_log(-1)   # NA
safe_log(10)   # 2.302585

# Variadic functions with ...
my_paste <- function(..., sep = " ") {
    args <- list(...)
    paste(args, collapse = sep)
}
my_paste("one", "two", "three", sep = "-")  # "one-two-three"

# Passing ... to another function
loud_mean <- function(x, ...) {
    result <- mean(x, ...)
    cat("Mean is:", result, "
")
    invisible(result)
}
loud_mean(c(1, 2, NA), na.rm = TRUE)   # Mean is: 1.5

# Closures: function factories
make_power <- function(exp) {
    function(x) x ^ exp    # captures 'exp' from enclosing env
}
square <- make_power(2)
cube   <- make_power(3)
square(4)   # 16
cube(3)     # 27

# Anonymous functions (lambda-style)
(function(x, y) x + y)(5, 3)   # 8
sapply(1:5, function(x) x * x)  # 1 4 9 16 25