examples: add a simple coroutine example

ROADMAP.md

@@ -1,8 +1,27 @@
+## [Version 0.3]
+
+-- [x] gc option
+-- [x] channels
+-- [x] lock{}
+-- [x] thread safe arrays
+-- [x] rune type
+-- [x] replace `ustring` with `[]rune`
+-- [x] fix `byte.str()`
+-- [x] maps with non-string keys
+-- [x] iOS/Android support
+-- [x] parallel cgen
+-- [x] IO streams
+-- [x] struct embedding
+-- [x] interface embedding
+-- [x] interfaces: allow struct fields (not just methods)
+-- [x] short generics syntax (`foo(5)` instead of `foo<int>(5)`)
+-- [x] more advanced errors, not just `error('message')`
+
 ## [Version 0.4]
 
 - [x] [Coroutines](https://github.com/vlang/v/discussions/11582)
 - [x] vfmt: add missing imports (like goimports)
-- [ ] Recursive structs via options: `struct Node { next ?Node }`
+- [x] Recursive structs via options: `struct Node { next ?Node }`
 - [x] First class Option type
 - [x] Optional function struct fields
 - [ ] Handle function pointers safely, remove `if function == 0 {`
@@ -13,6 +32,7 @@
 - [x] New VPM site
 
 ## [Version 0.5]
+
 - [ ] [Thread safe maps](https://github.com/vlang/v/discussions/11729)
 - [ ] Parallel parser
 - [ ] Parallel checker
@@ -29,6 +49,7 @@
 - [ ] Big remaining bugs fixed
 - [ ] More powerful comptime
 - [ ] Constraits for generics
+- [ ] Coroutines on Windows
 - [ ] Autofree memory management option ready for production
 - [ ] C2V supporting entire C99 standard
 

examples/coroutines/simple_coroutines.v

@@ -0,0 +1,37 @@
+// Build with
+// v -use-coroutines simple_coroutines.v
+//
+import coroutines
+import time
+
+fn foo(a int) {
+	for {
+		println('hello from foo() a=${a}')
+		coroutines.sleep(1 * time.second)
+	}
+}
+
+fn foo2(a int) {
+	for {
+		println('hello from foo2() a=${a}')
+		coroutines.sleep(2 * time.second)
+	}
+}
+
+fn foo3(a int) {
+	for {
+		println('hello from foo3() a=${a}')
+		coroutines.sleep(3 * time.second)
+	}
+}
+
+fn main() {
+	go foo(10)
+	go foo2(20)
+	go foo3(30)
+	for {
+		println('hello from MAIN')
+		coroutines.sleep(1 * time.second)
+	}
+	println('done')
+}

vlib/coroutines/coroutines.v

@@ -11,7 +11,7 @@ import time
 #include "photonwrapper.h"
 
 fn C.photon_init_default() int
-fn C.photon_thread_create(f voidptr)
+fn C.photon_thread_create(f voidptr, arg voidptr)
 fn C.photon_sleep_s(n int)
 fn C.photon_sleep_ms(n int)
 
@@ -21,5 +21,8 @@ pub fn sleep(duration time.Duration) {
 }
 
 fn init() {
-	C.photon_init_default()
+	ret := C.photon_init_default()
+	if ret < 0 {
+		panic('failed to initialize coroutines via photon (ret=${ret})')
+	}
 }