coroutines: $if is_coroutine? {

examples/coroutines/simple_coroutines.v

@@ -3,6 +3,8 @@
 //
 import coroutines
 import time
+import os
+import net.http
 
 fn foo(a int) {
 	for {
@@ -12,9 +14,17 @@ fn foo(a int) {
 }
 
 fn foo2(a int) {
+	mut i := 0
 	for {
 		println('hello from foo2() a=${a}')
 		coroutines.sleep(2 * time.second)
+		i++
+		// resp := http.get('https://vlang.io/utc_now') or { panic(err) }
+		// resp := http.get('http://example.com') or { panic(err) }
+		// println(resp)
+		// mut f := os.create('/tmp/FOO2_a${i}') or { panic(err) }
+		// f.write_string(resp.body) or { panic(err) }
+		// f.close()
 	}
 }
 
@@ -29,6 +39,11 @@ fn main() {
 	go foo(10)
 	go foo2(20)
 	go foo3(30)
+	$if is_coroutine ? {
+		println('IS COROUTINE=true')
+	} $else {
+		println('IS COROUTINE=false')
+	}
 	for {
 		println('hello from MAIN')
 		coroutines.sleep(1 * time.second)

vlib/v/pref/pref.v

@@ -813,6 +813,8 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 						os.system('wget -O "${so_path}" "${so_url}"')
 						println('done!')
 					}
+					res.compile_defines << 'is_coroutine'
+					res.compile_defines_all << 'is_coroutine'
 				} $else {
 					println('coroutines only work on arm64 macos for now')
 				}