Add structured coroutines and explicit error handling

internal/lang/token.go

@@ -20,6 +20,7 @@ const (
 	tokenEnum        tokenKind = "ENUM"
 	tokenMatch       tokenKind = "MATCH"
 	tokenFun         tokenKind = "FUN"
+	tokenSuspend     tokenKind = "SUSPEND"
 	tokenOverride    tokenKind = "OVERRIDE"
 	tokenPrivate     tokenKind = "PRIVATE"
 	tokenVal         tokenKind = "VAL"
@@ -65,17 +66,19 @@ const (
 	tokenAmp         tokenKind = "&"
 	tokenAt          tokenKind = "@"
 	tokenQuestion    tokenKind = "?"
+	tokenSafeDot     tokenKind = "?."
+	tokenDoubleBang  tokenKind = "!!"
 	tokenOr          tokenKind = "||"
 	tokenArrow       tokenKind = "->"
 )
 
 var keywords = map[string]tokenKind{
 	"fun":       tokenFun,
+	"suspend":   tokenSuspend,
 	"import":    tokenImport,
 	"package":   tokenPackage,
 	"class":     tokenClass,
 	"data":      tokenData,
-	"worker":    tokenWorker,
 	"interface": tokenInterface,
 	"enum":      tokenEnum,
 	"match":     tokenMatch,
@@ -90,7 +93,6 @@ var keywords = map[string]tokenKind{
 	"in":        tokenIn,
 	"select":    tokenSelect,
 	"return":    tokenReturn,
-	"go":        tokenGo,
 	"defer":     tokenDefer,
 	"try":       tokenTry,
 	"catch":     tokenCatch,