Do you have any examples of the second class?

The one that comes to mind is how big your hash maps have to get before all the clever algorithms beat linear scan, and it's surprisingly large on modern computers: linear memory access is _very_ predictable.

The Roc and Zig folks probably have actual numbers.

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tshaddox 3 hours ago | parent [-]

What are these surprisingly large numbers you've seen? I thought that linear scan optimizations are typically reserved for pretty small maps, like dozens or maybe hundreds of elements.

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inigyou an hour ago | parent [-]

Hundreds sounds about right, maybe up to a thousand.

But nobody expects that. Hashmap is supposed to be faster once you have, like, ten elements. That's what was promised to us.

	▲	zellyn an hour ago \| parent [-]
		Yeah, I found hundreds surprising (although not on reflection).

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mrkeen 4 hours ago | parent | prev | next [-]

Not sure if this counts, but I learned Huffman coding the intuitive tree-based way. From memory it was O(nlogn), but you can just O(n) it in-place in an array.

	▲	inigyou an hour ago \| parent [-]
		Huffman decoding you mean. All the fast decoders build tables processing N (8, 16, ...) bits at a time. If the next byte is 253 in state 6 that means output 15,28,28 and go to state 42... There are probably even faster ways I don't know of.

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jvanderbot 3 hours ago | parent | prev [-]

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