The argument selection function λfirst.λsecond.first accepts a function as an argument and returns a function which, when given an argument, returns the first argument. // λfirst.λsecond.first const selectFirst = x => y => x const double = a => a * 2 const triple = a => a * 3 const applyDouble = selectFirst(double) const applyTriple

Function application function is represented by the term λf.λx.f x. It accepts a function as an argument and applies it to the argument of the function it returns. // λf.λx.f x let apply f x = f x let addOne c = c + 1 let applyAddOne = addOne |> apply |> (fun