Create a typed function

Defines a function with specified parameter types and return type. Ensures that the function's arguments and return value adhere to the specified types.

Usage

fun(...)

Arguments

...

Named arguments defining the function parameters and their types, including 'return' for the expected return type(s) and 'impl' for the function implementation.

Value

A function of class 'typed_function' that enforces type constraints on its parameters and return value. The returned function has the same signature as the implementation function provided in the 'impl' argument.

Details

The `fun` function allows you to define a function with strict type checking for its parameters and return value. This ensures that the function receives arguments of the correct types and returns a value of the expected type. The 'return' and 'impl' arguments should be included in the ... parameter list.

Examples

# Define a typed function that adds two numbers
add_numbers <- fun(
  x = numeric,
  y = numeric,
  return = numeric,
  impl = function(x, y) {
    return(x + y)
  }
)

# Valid call
print(add_numbers(1, 2))  # [1] 3
#> [1] 3

# Invalid call (throws error)
try(add_numbers("a", 2))
#> Error : Property 'x' must be of type numeric

# Define a typed function with multiple return types
concat_or_add <- fun(
  x = c(numeric, character),
  y = numeric,
  return = c(numeric, character),
  impl = function(x, y) {
    if (is.numeric(x)) {
      return(x + y)
    } else {
      return(paste(x, y))
    }
  }
)

# Valid calls
print(concat_or_add(1, 2))     # [1] 3
#> [1] 3
print(concat_or_add("a", 2))   # [1] "a 2"
#> [1] "a 2"