FYI, you can achieve the same thing with F# pipelines + partial application proposal [1] input |> func(?, 2) input |> func(1, ?) While hack's placeholders

FYI, you can achieve the same thing with F# pipelines + partial application proposal [1] input |> func(?, 2) input |> func(1, ?) While hack's placeholders work exclusively in pipelines, the partial application proposal can be used with any function "123" .split("") .map(parseInt(?)) // make sure radix param is not set [1] https://github.com/tc39/proposal-partial-application https://github.com/tc39/proposal-partial-application