Lazy initialize process redirection channels

src/lazy_init.mbt

@@ -81,6 +81,18 @@ pub async fn[X] Lazy::wait(self : Lazy[X]) -> X {
   }
 }
 
+///|
+/// Return the result of a lazy value if is already computed,
+/// or return `None` if the result is not immediately available.
+/// Fail with the same error if the initialization process failed.
+pub fn[X] Lazy::try_wait(self : Lazy[X]) -> X? raise {
+  match self.state {
+    Done(result) => Some(result)
+    Fail(err) => raise err
+    Running(_) | Uninitialized => None
+  }
+}
+
 ///|
 /// Create a new lazily initialized value by passing an async initialization function.
 /// The function `f` will be started in the background automatically

src/os_error/errno_linux.mbt

@@ -41,3 +41,6 @@ let linux_EINPROGRESS : Int = 115
 
 ///|
 let linux_EWOULDBLOCK : Int = linux_EAGAIN
+
+///|
+let linux_EPIPE : Int = 32

src/os_error/errno_macos.mbt

@@ -41,3 +41,6 @@ let macos_EINPROGRESS : Int = 36
 
 ///|
 let macos_EWOULDBLOCK : Int = macos_EAGAIN
+
+///|
+let macos_EPIPE : Int = 32

src/os_error/errno_windows.mbt

@@ -44,3 +44,6 @@ let windows_ERROR_DIRECTORY : Int = 267
 
 ///|
 let windows_ERROR_NOT_SUPPORTED : Int = 50
+
+///|
+let windows_ERROR_BROKEN_PIPE : Int = 109

src/os_error/error.mbt

@@ -182,3 +182,10 @@ pub let errno_ENOTSUP : Int = match @env_util.platform {
   MacOS => macos_ENOTSUP
   Windows => windows_ERROR_NOT_SUPPORTED
 }
+
+///|
+pub let errno_EPIPE : Int = match @env_util.platform {
+  Linux => linux_EPIPE
+  MacOS => macos_EPIPE
+  Windows => windows_ERROR_BROKEN_PIPE
+}

src/os_error/pkg.generated.mbti

@@ -8,6 +8,8 @@ pub let errno_ENOTDIR : Int
 
 pub let errno_ENOTSUP : Int
 
+pub let errno_EPIPE : Int
+
 pub fn errno_to_string(Int) -> String
 
 pub fn get_errno() -> Int

src/pkg.generated.mbti

@@ -60,6 +60,7 @@ type Lazy[X]
 #as_free_fn(lazy_init, deprecated)
 #callsite(autofill(loc))
 pub fn[X] Lazy::Lazy(async () -> X, loc~ : SourceLoc) -> Self[X]
+pub fn[X] Lazy::try_wait(Self[X]) -> X? raise
 pub async fn[X] Lazy::wait(Self[X]) -> X
 
 type Mutex

src/process/pkg.generated.mbti

@@ -23,13 +23,13 @@ pub fn graceful_cancel(timeout~ : Int, signal? : @signal.Signal) -> Cancellation
 
 pub fn hard_cancel() -> CancellationHandler
 
-pub fn pipe() -> (&ProcessInput, &ProcessOutput) raise
+pub fn pipe() -> (&ProcessInput, &ProcessOutput)
 
-pub fn read_from_process(shared? : Bool) -> (ReadFromProcess, &ProcessOutput) raise
+pub fn read_from_process(shared? : Bool) -> (ReadFromProcess, &ProcessOutput)
 
-pub async fn redirect_from_file(String) -> &ProcessInput
+pub fn redirect_from_file(String) -> &ProcessInput
 
-pub async fn redirect_to_file(String, append? : Bool, create_mode? : @fs.CreateMode, permission? : Int, shared? : Bool) -> &ProcessOutput
+pub fn redirect_to_file(String, append? : Bool, create_mode? : @fs.CreateMode, permission? : Int, shared? : Bool) -> &ProcessOutput
 
 pub async fn run(StringView, ArrayView[String], extra_env? : Map[String, String], inherit_env? : Bool, stdin? : &ProcessInput, stdout? : &ProcessOutput, stderr? : &ProcessOutput, cwd? : StringView, no_console_window? : Bool, cancel_handler? : CancellationHandler) -> Int
 
@@ -39,7 +39,7 @@ pub async fn spawn_orphan(StringView, ArrayView[String], extra_env? : Map[String
 
 pub async fn wait_pid(Int) -> Int
 
-pub fn write_to_process() -> (&ProcessInput, WriteToProcess) raise
+pub fn write_to_process() -> (&ProcessInput, WriteToProcess)
 
 // Errors