Added the -stdout switch

_docs/mod/csv.md

@@ -28,8 +28,10 @@ csv:each-record "winds.csv" { |row hdr|
 }
 ```
 
+### to-csv
+
 ```
-csv:to-csv CONT [-header HEADER]
+csv:to-csv CONT [-header HEADER] [-stdout]
 ```
 
 Produces a CSV using the items of CONT and writes it as a string. CONT must be a list of iterator of hashable
@@ -37,4 +39,6 @@ elements.
 
 If HEADER is defined, it must be a list of strings identifying the name and order of the hash keys to read
 from each hashable item of CONT. If HEADER is not defined, then the keys of the first consumed hashable item will be
-used, with the keys sorted in alphabetical order.
+used, with the keys sorted in alphabetical order.
+
+If `-stdout` is set, the CSV will be written to standard out and `to-csv` will return the empty string.

ucl/builtins/csv.go

@@ -144,7 +144,15 @@ func (h csvHandlers) toCsv(ctx context.Context, args ucl.CallArgs) (any, error)
 	}
 
 	var sb strings.Builder
-	cw := csv.NewWriter(&sb)
+
+	var w io.Writer
+	if args.HasSwitch("stdout") {
+		w = os.Stdout
+	} else {
+		w = &sb
+	}
+
+	cw := csv.NewWriter(w)
 
 	i := 0
 	for {

ucl/builtins/csv_test.go

@@ -53,6 +53,11 @@ func TestCSV_ReadRecord(t *testing.T) {
 }
 
 func TestCSV_ToCSV(t *testing.T) {
+	type testStruct struct {
+		Alpha string
+		Bravo string
+	}
+
 	tests := []struct {
 		descr string
 		eval  string
@@ -78,6 +83,16 @@ func TestCSV_ToCSV(t *testing.T) {
 			eval:  `itrs:from [[hello:"one" world:"this"] [hello:"two" other:"the" world:"that"]] | csv:to-csv -header [world other]`,
 			want:  "world,other\nthis,\nthat,the\n",
 		},
+		{
+			descr: "to csv 5",
+			eval:  `test-native | csv:to-csv`,
+			want:  "Alpha,Bravo\nHello,World\nAnother,Test\n",
+		},
+		{
+			descr: "to csv 6",
+			eval:  `test-native | itrs:from | csv:to-csv`,
+			want:  "Alpha,Bravo\nHello,World\nAnother,Test\n",
+		},
 	}
 
 	for _, tt := range tests {
@@ -89,6 +104,12 @@ func TestCSV_ToCSV(t *testing.T) {
 				ucl.WithModule(builtins.Itrs()),
 				ucl.WithOut(&bfr),
 			)
+			inst.SetBuiltin("test-native", func(ctx context.Context, args ucl.CallArgs) (any, error) {
+				return []testStruct{
+					{Alpha: "Hello", Bravo: "World"},
+					{Alpha: "Another", Bravo: "Test"},
+				}, nil
+			})
 
 			res, err := inst.Eval(context.Background(), tt.eval)
 			assert.NoError(t, err)