Add MVP port stuff

has a cast() that I don't want a recursive process import that breaks
things

also sucks to split up a datatype into receive/ due to conflicts

but, works when there's no recursive import

Fixes #89

Author: mjsir911

src/gleam/erlang/port.gleam

@@ -7,3 +7,72 @@
 /// [1]: https://erlang.org/doc/reference_manual/ports.html
 ///
 pub type Port
+
+
+import gleam/erlang/port
+import gleam/erlang/atom
+import gleam/erlang/process
+import gleam/erlang/port/receive
+import gleam/dynamic
+
+pub type PortName {
+  Spawn(String)
+  SpawnDriver(String)
+  SpawnExecutable(String)
+  Fd(in: Int, out: Int)
+}
+
+pub fn spawn(command: String) -> PortName {
+  Spawn(command)
+}
+
+pub fn spawn_driver(command: String) -> PortName {
+  SpawnDriver(command)
+}
+
+pub fn spawn_executable(command: String) -> PortName {
+  SpawnExecutable(command)
+}
+
+
+pub type PortOptions {
+  Arg0(String)
+  Args(List(String))
+  Env(List(#(String, String)))
+  Cd(String)
+  Binary
+
+  UseStdio
+  NouseStdio
+
+  Eof
+  ExitStatus
+
+  Stream
+  Line(Int)
+  Packet(Int) // only 1, 2, & 4
+}
+
+
+@external(erlang, "erlang", "open_port")
+fn open_port(
+  name: PortName,
+  settings: List(PortOptions),
+) -> Port
+
+@external(erlang, "erlang", "port_command")
+fn port_command(
+  port: Port,
+  data: BitArray,
+  options: List(PortOptions),
+) -> Nil
+
+
+@external(erlang, "gleam_stdlib", "identity")
+@external(javascript, "../gleam_stdlib.mjs", "identity")
+fn cast(a: anything) -> dynamic.Dynamic
+
+pub fn open(command: PortName, settings: List(PortOptions)) -> process.Subject(receive.PortData) {
+  let port = open_port(command, settings)
+  process.unsafely_create_subject(process.self(), cast(port))
+}

src/gleam/erlang/port/receive.gleam

@@ -0,0 +1,5 @@
+pub type PortData {
+  Data(BitArray)
+  ExitStatus(Int)
+  Eof
+}

test/gleam/erlang/port_test.gleam

@@ -0,0 +1,10 @@
+pub fn port_open_test() {
+  let subject = port.run_open_port(
+    port.spawn_executable("/bin/bash"),
+    [port.Args(["-c", "echo hi | wc -c"]), port.UseStdio, port.ExitStatus, port.Binary]
+  )
+  assert Ok(receive.Data(<<"3\n">>)) == process.receive(subject, 100) 
+  assert Ok(receive.ExitStatus(0)) == process.receive(subject, 100) 
+  assert Error(Nil) == process.receive(subject, 100) 
+}
+