The async block syntax would be nice, and probably far more explicit. I think with the `return alpha + beta + gamma` the idea is that within a scope, everythin

The async block syntax would be nice, and probably far more explicit. I think with the `return alpha + beta + gamma` the idea is that within a scope, everything is done as late as possible, but you can't leave a scope without all results. Thus, if the code is expanded as: alpha = run_a() beta = run_b() gamma = run_c() a_plus_b = plus(alpha, beta) sum = plus(a_plus_b, gamma) return sum In that case, the compiler has to determine a partial ordering: a_plus_b <- run_a, run_b sum <- a_plus_b, run_c Thus it can generate: await gather(run_a, run_b, run_c) await plus(alpha, beta) await plus(a_plus_b, gamma) And presumably you can detect pure subroutine / primitive invocations. And there would be other hard points where tasks must be fully awaited; e.g. loops wouldn't be able to leak tasks.