Generators (original) (raw)

Brian Goetz brian.goetz at oracle.com
Thu Jan 3 12:41:45 PST 2013

Related to generators is array pre-filling.

Originally I'd though we might want

Arrays.fill(arr, Supplier)

but that gets doubled with {fill,parallelFill} versions. A possibly more general approach is:

IntStream Arrays.indexes(array)

which would generate an intRange(0, array.length). Then filling becomes

Arrays.indexes(array).forEach(i -> array[i] = ...) or in parallel Arrays.indexes(array).parallel().forEach(i -> array[i] = ...)

This also subsumes other use cases like replaceAll, conditional replace, etc, with less library code.

On 1/3/2013 2:49 PM, Brian Goetz wrote:

I'm looking over our generators. Currently we have:

repeat(T) repeat(n, T) repeatedly(Supplier) repeatedly(n, Supplier) iterate(T, UnaryOperator) cycle(Iterable) I'd like to pare this down a lot. Paul and I have been discussing techniques for making limit() more efficient, at which point the first four can collapse to generate(Supplier) since you can simulate repeat(T) with generate(() -> T) and the limited versions with generate().limit(). That leaves us with iterate(T, UnaryOperator) cycle(Iterable) and I'm thinking cycle doesn't pull its weight either. If we took that out, we'd be down to the pleasantly small set of: generate(Supplier) iterate(T, UnaryOperator) For integer generators, we have range(from, to) and I think we should add ints() -> sugar for range(0, MAXINT) (Or should ints() be truly infinite, wrapping around?)

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