A first poor attempt

spago.dhall

@@ -15,6 +15,7 @@ You can edit this file as you like.
   , "effect"
   , "either"
   , "enums"
+  , "exceptions"
   , "foldable-traversable"
   , "foreign-object"
   , "free"
@@ -26,7 +27,10 @@ You can edit this file as you like.
   , "maybe"
   , "node-buffer"
   , "node-child-process"
+  , "node-event-emitter"
   , "node-fs"
+  , "node-os"
+  , "node-streams"
   , "nonempty"
   , "ordered-collections"
   , "parsing"
@@ -37,6 +41,7 @@ You can edit this file as you like.
   , "strings"
   , "transformers"
   , "tuples"
+  , "unsafe-coerce"
   , "web-dom"
   , "web-url"
   , "yoga-tree"

src/Main.purs

@@ -2,14 +2,23 @@ module Main where
 
 import Prelude
 
+import Data.Either (Either(..))
 import Data.Maybe (Maybe(..))
 import Effect (Effect)
-import Effect.Class.Console (log)
+import Effect.Aff (Aff, effectCanceler, launchAff_, makeAff)
+import Effect.Class (liftEffect)
+import Effect.Class.Console (log, logShow)
+import Effect.Exception (throw, throwException)
 import Node.Buffer (toString)
-import Node.ChildProcess (ExecResult)
+import Node.ChildProcess (ExecResult, connected, exitCode, spawn, stdout)
 import Node.ChildProcess as ChildProcess
+import Node.ChildProcess.Aff (waitSpawned)
+import Node.ChildProcess.Types (Exit(..))
 import Node.Encoding (Encoding(..))
 import Node.Errors.SystemError (code, message)
+import Node.EventEmitter (EventHandle, once)
+import Node.Stream (read)
+import Unsafe.Coerce (unsafeCoerce)
 
 
 main :: Effect Unit
@@ -17,6 +26,12 @@ main = do
   log "hello"
   _ <- ChildProcess.exec' "pwd" identity readExec
   _ <- ChildProcess.exec' "touch /test.log" identity readExec
+
+  execCmd "pwd"
+  execCmd "touch /test.log"
+
+  launchAff_ spawnLs
+
   pure unit
 
 readExec ∷ ExecResult → Effect Unit
@@ -27,3 +42,43 @@ readExec {error: Nothing, stdout, stderr} = do
 
 readExec {error: Just err, stdout, stderr} = do
   log $ "error ! [" <> code err <> "], " <> message err
+
+execCmd str = do
+  cp <- ChildProcess.exec str
+  exit <- exitCode cp
+  case exit of
+    Nothing -> log "exit with Nothing"
+    Just 0 -> log "exit with 0"
+    Just i -> log $ "exit with " <> show i
+
+spawnLs :: Aff Unit
+spawnLs = do
+  log "\nspawns processes ok"
+  ls <- liftEffect $ spawn "ls" [ "-la" ]
+  res <- waitSpawned ls
+  case res of
+    Right pid -> log $ "ls successfully spawned with PID: " <> show pid
+    Left err -> liftEffect $ throwException $ unsafeCoerce err
+  exit <- until ls ChildProcess.closeH \complete -> \exit -> complete exit
+  case exit of
+    Normally 0 -> do 
+      log $ "ls exited with 0"
+      out <- liftEffect $ read $ stdout ls
+      case out of 
+        Nothing -> log "Could not get stdout"
+        Just out' -> do
+          outStr <- liftEffect $ toString UTF8 out'
+          logShow outStr
+      
+    Normally i -> liftEffect $ throw $ "ls had non-zero exit: " <> show i
+    BySignal sig -> liftEffect $ throw $ "ls exited with sig: " <> show sig
+
+until
+  :: forall emitter psCb jsCb a
+   . emitter
+  -> EventHandle emitter psCb jsCb
+  -> ((a -> Effect Unit) -> psCb)
+  -> Aff a
+until ee event cb = makeAff \done -> do
+  rm <- ee # once event (cb (done <<< Right))
+  pure $ effectCanceler rm