Primary dispatcher for functional programming

UseFunction manages the dispatching for multipart functions in lambda.r. This is used internally by lambda.r.

Usage

UseFunction(fn, fn.name, ...)
NewObject(type.fn, type.name, ...)

Arguments

fn

The function reference that is being applied

fn.name

The name of a function that uses functional dispatching. This is just the name of the function being defined

type.fn

The function representing the type constructor

type.name

The name of the type

...

The arguments that are passed to dispatched functions

Details

This function is used internally and generally does not need to be called by an end user.

Value

Returns the value of the dispatched function

Author

Brian Lee Yung Rowe

See also

%as%

Examples

# Note that these are trivial examples for pedagogical purposes. Due to their
# trivial nature, most of these examples can be implemented more concisely
# using built-in R features.


reciprocal(x) %::% numeric : numeric
reciprocal(x) %when% {
  x != 0
} %as% {
  1 / x
}

reciprocal(x) %::% character : numeric
reciprocal(x) %as% {
  reciprocal(as.numeric(x))
}

seal(reciprocal)

print(reciprocal)
#> <function>
#> [[1]]
#> reciprocal(x) %::% numeric:numeric 
#> reciprocal(x) %when% {
#>     x != 0
#> } %:=% ...
#> [[2]]
#> reciprocal(x) %::% character:numeric 
#> reciprocal(x) %:=% ...
reciprocal(4)
#> [1] 0.25
reciprocal("4")
#> [1] 0.25