[evincarofautumn]

One practical way to implement this would be a “...” operator which would look at the syntax of the surrounding expression and attempt to infer an inductive definition from that, based on some assumptions about e.g. the structure of lists or the values of integers.

    double xs => [xs[0] * 2, ..., xs[xs.length - 1] * 2]

    map f xs => [f(xs[0]), ..., f(xs[xs.length - 1])]

    sum xs => xs[0] + ... + xs[xs.length - 1]

    foldl f z xs => f(f(..., f(z, xs[0])), xs[xs.length - 1])

    foldr f z xs => f(xs[0], f(..., f(xs[xs.length - 1], z)))