deriveCompose: make it variadic

[awalterschulze]

Also rename deriveBind to deriveCompose

[awalterschulze]

Then we can write

getEndpoint := fmt.Sprintf("%s/oldusers/%s", config.endpoint, config.username)
postEndpoint := fmt.Sprintf("%s/newusers/%s", config.endpoint, config.username)

result, err := deriveCompose(
    http.Get(getEndpoint),
    func(req *http.Request) ([]byte, error) { return ioutil.ReadAll(req.Body) },
    user.NewFromJson,
    user.NewUserFromUser,
    json.Marshal,
    func(buf []byte) (*http.Response, error) {
        return http.Post(postEndpoint, "application/json", bytes.NewBuffer(buf))
    },
)

Example found on slide 55 of https://speakerdeck.com/rebeccaskinner/monadic-error-handling-in-go

[mh-cbon]

crazy shit. That is awesome.

[awalterschulze]

Glad you like it :)

[awalterschulze]

done and also included an example https://github.com/awalterschulze/goderive/tree/master/example/plugin/compose