tricu

A lazy functional language based on Tree Calculus
Log | Files | Refs | README | LICENSE

53b86101d6aa83cce2d7217c168602faca01b9985be46b910b6579096e959ad1.tri (1281B)

      1 !import base as B
      2 !import io as IO
      3 !import io_text as Text
      4 !export main
      5 !export asyncDemo
      6 
      7 -- Explicit IO sequencing, scoped children and consumed join tickets. Sleep
      8 -- permits other work, but promises neither exact wakeup time nor task ordering.
      9 -- Only the parent writes stdout: concurrent writers need explicit coordination,
     10 -- not an assumption that yield/sleep makes a multi-write message atomic.
     11 line text = IO.require IO.stdout (writer : Text.writeText writer (B.append text "\n"))
     12 waitFor [_ ticket] = IO.require (IO.join ticket) (outcome : case outcome of
     13   ["completed" value] = IO.pure value
     14   ["cancelled" reason _] = IO.cancelled reason
     15   ["failed" problem cleanup] = IO.fail [problem cleanup]
     16   _ = IO.fail "Invalid task outcome")
     17 waitFor _ = IO.fail "Invalid spawn reply"
     18 worker milliseconds message = IO.require (IO.sleepMilliseconds milliseconds) (_ : IO.pure message)
     19 asyncDemo = IO.scope (_ : do IO.require
     20   first <- IO.spawn 0 1 [] (_ : worker 2000 "2000ms done sleeping!")
     21   second <- IO.spawn 0 1 [] (_ : worker 5000 "5000ms done sleeping!")
     22   line "Parent first!"
     23   IO.bind (waitFor first) (message : IO.require (line message) (_ :
     24     IO.bind (waitFor second) (message : IO.require (line message) (_ : IO.pure "child2000 done")))))
     25 main = IO.io asyncDemo