feat: add unlinked-spawn to the C and Zig APIs

include/thespian/c/instance.h

@@ -28,6 +28,9 @@ thespian_handle thespian_self();
 int thespian_spawn_link(thespian_behaviour, thespian_behaviour_state,
                         const char *name, thespian_env, thespian_handle *);
 
+int thespian_spawn(thespian_behaviour, thespian_behaviour_state,
+                   const char *name, thespian_env, thespian_handle *);
+
 #ifdef __cplusplus
 }
 #endif

src/c/instance.cpp

@@ -96,4 +96,30 @@ auto thespian_spawn_link(thespian_behaviour b, thespian_behaviour_state s,
       new thespian::handle{ret.value()});
   return 0;
 }
+
+auto thespian_spawn(thespian_behaviour b, thespian_behaviour_state s,
+                    const char *name, thespian_env env, thespian_handle *handle)
+    -> int {
+  const thespian::env_t empty_env_{};
+  thespian::env_t env_ =
+      env ? *reinterpret_cast<thespian::env_t *>(env) : empty_env_; // NOLINT
+
+  auto ret = spawn(
+      [b, s]() -> thespian::result {
+        auto *ret = b(s);
+        if (ret) {
+          auto err = cbor::buffer();
+          const uint8_t *data = ret->base;                      // NOLINT
+          std::copy(data, data + ret->len, back_inserter(err)); // NOLINT
+          return thespian::to_error(err);
+        }
+        return thespian::ok();
+      },
+      string_view(name), std::move(env_));
+  if (!ret)
+    return -1;
+  *handle = reinterpret_cast<thespian_handle>( // NOLINT
+      new thespian::handle{ret.value()});
+  return 0;
+}
 }

src/thespian.zig

@@ -584,6 +584,28 @@ pub fn spawn_link(
     return spawn_link_env(a, data, f, name, env.get());
 }
 
+/// Spawn a new actor WITHOUT creating a link to the calling actor.
+/// The new actor runs independently; its exit does not propagate to the
+/// caller. Think twice before you use this form of spawn. It's rarely want
+/// you want to do.
+pub fn spawn(
+    a: std.mem.Allocator,
+    data: anytype,
+    f: Behaviour(@TypeOf(data)).FunT,
+    name: [:0]const u8,
+) error{ OutOfMemory, ThespianSpawnFailed }!pid {
+    const Tclosure = Behaviour(@TypeOf(data));
+    var handle_: c.thespian_handle = null;
+    try neg_to_error(c.thespian_spawn(
+        Tclosure.run,
+        try Tclosure.create(a, f, data),
+        name,
+        env.get().env,
+        &handle_,
+    ), error.ThespianSpawnFailed);
+    return wrap_pid(handle_);
+}
+
 pub fn spawn_link_env(
     a: std.mem.Allocator,
     data: anytype,