[lotheac]

This is a prime example of useless use of cat. Heredoc already means "pass this as stdin", there's no need to pipe it. Your example without cat:

    curl http://localhost -d @- <<REQUEST_BODY
    {
      "from" : 0,
      "size" : 40
    }
    REQUEST_BODY

[pdkl95]

I like modularity:

    request_body() {
        cat <<REQUEST_BODY |      
        {
            "from" : 0,
            "size" : 40
        }
        REQUEST_BODY
    }

    get_url() {
        curl http://localhost -d @-
    }

    request_body | get_url

I find it helps readability when you come back to it a year later. Of course, it's also easy to parameterize the body, if needed.

/readability sometimes trumps YAGNI

[mateuszf]

Well, maybe in that case it is. But I like to separate the commands so that the data flow looks sequential. That way it makes more sense to me.

[zimpenfish]

Much as I hate the cargocult invocation of "UUOC", this is actually nicer because it reads more sanely - the HEREDOC is properly linked to the curl whereas the previous has the curl seemingly adrift on its own line unattached to the HEREDOC.