Pair sensors with readings, keep anomalies
Requirement
A telemetry API returns two parallel lists: sensor names and their latest temperature readings, matched by position. Pair them up, keep the readings above 90.0 °C, and print one alert line per anomaly, in list order. The data is in the code below; both versions must print the lines shown under Expected output.
Expected output
boiler-2: 104.6 °C pump-b: 93.4 °C vent-7: 97.1 °C
Side by side
Native Dart
FxDart
Why they differ
Core Dart has no zip. package:collection offers
IterableZip, but it zips same-typed iterables — pairing a
List<String> with a List<double>
degrades both to Object and puts casts in your predicate —
so in practice Dart developers write the index loop shown here instead.
The loop is correct, but the pairing lives in positional bookkeeping
(sensors[i], readings[i]) and produces nothing
you can pass along or filter further. FxDart's zip yields
typed (String, double) record pairs, so the anomaly check
and the formatting stay ordinary chain steps over real values.
Benchmark
N = 100
Time Tie
Peak memory Tie
N = 10,000
Time Tie
Peak memory Tie
N = 1,000,000
Time Native wins
Peak memory FxDart wins
Bars are medians of repeated timed iterations in fresh processes per side (small N is batched for timer resolution). Sides within 5% of each other — or within 0.6 ms, a difference no person can perceive — count as a tie; close relative races are re-measured up to 5 runs. In an app, anything under a few milliseconds is invisible to the user regardless of which bar is shorter. Memory is peak process RSS. The Dart VM and the dataset are identical on both sides, so the difference between the two bars is what the pipeline itself holds onto.