Best practice for passing parameters to functions passed as parameters

General Usage
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3

Maybe you could use keyword arguments Functions · The Julia Language

The differences to optional arguments is that the order doesn’t matter but only the keywords. Notices that one uses ; instead of , to capture keyword argument lists.
E.g.

function myfunction(input::AbstractMatrix,
                    preprocess::Function,
                    updater!::Function;
                    args...
                    )
    A = preprocess(input; args...)

    # Some common code
    # [...]

    for i in 1:100
        # Some common code
        # [...]
        updater!(A; args...)
    end

    # Some common code
    # [...]

    return A
end

For the user calling your function it is enough to write

myfunction(input, preprocess, updater!, alpha = 10, beta = 4 )