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author | sterni <sternenseemann@systemli.org> | 2021-11-22T21·06+0100 |
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committer | sterni <sternenseemann@systemli.org> | 2021-11-23T13·22+0100 |
commit | 8615322bc81dfe106aa158b95567300372ea469d (patch) | |
tree | 83fe1e4eebe2df260183e4c298738b07a98537d5 /users/Profpatsch/netencode/default.nix | |
parent | a2be05faa4043c225581090846c52718812fac8f (diff) |
refactor(sterni/nix/utf8): use genericClosure for decoding iteration r/3085
builtins.genericClosure is a quite powerful (and undocumented) Nix primop: It repeatedly applies a function to values it produces and collects them into a list. Additionally individual results can be identified via a key attribute. Since genericClosure only ever creates a single list value internally, we can eliminate a huge performance bottleneck when building a list in a recursive algorithm: list concatenation. Because Nix needs to copy the entire chunk of memory used internally to represent the list, building big lists one element at a time grinds Nix to a halt. After rewriting decode using genericClosure decoding the LaTeX source of my 20 page term paper now takes 2s instead of 14min. Change-Id: I33847e4e7dd95d7f4d78ac83eb0d74a9867bfe80
Diffstat (limited to 'users/Profpatsch/netencode/default.nix')
0 files changed, 0 insertions, 0 deletions