Marshal/Encode result of a float value without decimal part is not same with go-yaml/yaml

[apstndb]

Marshal result of a float value without decimal part is not same with go-yaml/yaml.

package main

import (
	goccyyaml "github.com/goccy/go-yaml"
	goyaml "gopkg.in/yaml.v3"
	"os"
)

func main() {
	goyaml.NewEncoder(os.Stdout).Encode(1.0)
	goccyyaml.NewEncoder(os.Stdout).Encode(1.0)
}

1
1.0

This behavior is not also same with JSON marshalers and not comfortable when roundtrip.

[philomory]

I'd say that both go-yaml/yaml and goccy/yaml are incorrect.

Outputing a 1 for a float value of 1.0 is incorrect, by my reading of the YAML spec; it means that float values don't round-trip correctly, because when you read it back in, it will be an int instead. Note that this isn't aesthetic; YAML is a typed file format, and an untagged 1 is an int, not a float.

goccy/yaml correctly outputs 1.0 for a float value of 1.0, but, unfortunately, it weirdly fails to support float values with more than seven digits after the decimal point: https://play.golang.org/p/n9z9jZ2dPBI, a case that go-yaml actually handles correctly.

I'd say that ideally the correct method would be to use strconv.FormatFloat the way go-yaml does, but then check if the resulting string contains a . (or scientific notation) and, if not, append .0.