Concurrency.select.start: def of bend-kit-concurrency@0.2.0.0
Import: import bend-kit-concurrency@0.2.0.0/concurrency.bend as Concurrency
Lines 279-292 of bend-kit-concurrency@0.2.0.0/concurrency.bend: https://jend.leeeet.dev/read.txt?path=bend-kit-concurrency@0.2.0.0/concurrency.bend&start_line=279&end_line=292

import Base

# ponytail: relay fuel is the largest Nat literal, and a value takes three
# steps, so a relay stops after about 1.4 billion values. Drop the fuel if
# Base gains an unbounded loop.
def select.start(
  -A: Type, chans: List<Chan(A)>, +i: U32, +out: Chan(U32 & A), +done: Chan(Unit)
) -> IO(Nat):
  match chans:
    case Nil{}:
      IO.pure(Nat, 0n)
    case src <> rest:
      do IO<Nat>:
        IO.spawn(Result<&1, &1, Unit, Unit>, select.relay(A, 4294967295n, i, src, out, done, RWait{}))
        n : Nat <- select.start(A, rest, (i + 1 : U32), out, done)
        return 1n+n

Uses (14):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Chan
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=IO
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=IO.bind
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=IO.pure
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=IO.spawn
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Result
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Unit
  https://jend.leeeet.dev/definition.txt?path=bend-kit-concurrency@0.2.0.0/concurrency.bend&name=Relay
  https://jend.leeeet.dev/definition.txt?path=bend-kit-concurrency@0.2.0.0/concurrency.bend&name=select.relay