Rename ReturnField to OptionalField

internal/generate/gocode/gotemplate/func.go

@@ -62,7 +62,7 @@ func signature(f truce.Function) string {
 	}
 
 	builder.WriteString(") (")
-	if rtn := f.Return; !rtn.NoReturn && rtn.Name != "" {
+	if rtn := f.Return; rtn.Present && rtn.Name != "" {
 		fmt.Fprintf(builder, "%s, ", goType(rtn.Type))
 	}
 	builder.WriteString("error)")

internal/generate/gocode/gotemplate/func_test.go

@@ -136,9 +136,12 @@ func TestSignature(t *testing.T) {
 				Arguments: []truce.Field{
 					{Name: "a", Type: "string"},
 				},
-				Return: &truce.Field{
-					Name: "x",
-					Type: "string",
+				Return: truce.OptionalField{
+					Present: true,
+					Field: truce.Field{
+						Name: "x",
+						Type: "string",
+					},
 				},
 			},
 			out: "do(ctxt context.Context, a string) (string, error)",

internal/generate/gocode/gotemplate/http.go

@@ -270,7 +270,7 @@ func NewFunction(config *truce.HTTP, function truce.Function) (*Function, error)
 		}
 	}
 
-	if !function.Return.NoReturn && function.Return.Name != "" {
+	if function.Return.Present && function.Return.Name != "" {
 		b.HasReturn = true
 		b.ReturnType = string(function.Return.Type)
 

openapi.cue

@@ -167,7 +167,7 @@ openapi3: {
 								responses: {
 									"200": {
 										description: "\(fnDef.name) operation 200 response"
-										if !fnDef.return.noReturn {
+										if fnDef.return.present {
 											content: {
 												"application/json": {
 													_#schemaObj & {schema: {_type: fnDef.return.type}}

spec.go

@@ -79,15 +79,17 @@ type HTTPError struct {
 }
 
 type Function struct {
-	Name      string  `cue:"name"`
-	Arguments []Field `cue:"arguments"`
-	Return    struct {
-		Field
-		NoReturn bool `cue:"noReturn"`
-	} `cue:"return"`
+	Name       string            `cue:"name"`
+	Arguments  []Field           `cue:"arguments"`
+	Return     OptionalField     `cue:"return"`
 	Transports FunctionTransport `cue:"transports"`
 }
 
+type OptionalField struct {
+	Field
+	Present bool `cur:"present"`
+}
+
 // FunctionTransport to be defined at a later date.
 type FunctionTransport struct {
 	HTTP *HTTPFunction `cue:"http"`

truce.cue

@@ -52,7 +52,7 @@ specifications: [n=string]: [v=string]: #API & {name: n, version: v}
 #Function: {
 	name: =~"^[A-Z][a-zA-Z]*$" // function names are capitalised
 	arguments: [...#Field]
-	return: *({noReturn: true}) | #ReturnField
+	return: *({present: false}) | #OptionalField
 	transports?: http?: #HTTPFunction
 }
 
@@ -72,8 +72,8 @@ specifications: [n=string]: [v=string]: #API & {name: n, version: v}
 	type: or(#all) | =~"map[[][*]?[A-Za-z]+[]][*]?[A-Za-z]+" | =~"^[*]?[A-Z][a-zA-Z]*$" | =~"^[[][]][*]?[A-Z][a-zA-Z]*?" // can be primitive, Custom, *Custom, []primitive, []Custom, []*Custom.
 }
 
-#ReturnField: {
-	noReturn: bool | *false
+#OptionalField: {
+	present: bool | *true
 	#Field
 }