How can you populate multi command help

[lwdye]

How can you set help strings for commands? I'm able to generate help for individual flags but not for the commands themselves. Suppose we have

data Commands = Hello{myflag::String <?> "it works!"} | Goodbye deriving (Show, Generic)

How can one generate the help "Print greeting" and "Say goodbye" for hello and goodbye as below. The mechanism is available in the underlying Options.Applicative.

Usage: commands COMMAND

Available options:
  -h,--help                Show this help text

Available commands:
  hello                    Print greeting
  goodbye                  Say goodbye

[Gabriella439]

I don't think there is a good way to do this within this library's framework

[lwdye]

Thank you. Yes, I was also stuck seeing how to do this cleanly. One idea is to "somehow" use the type specification to generate unique tags / enums / strings as keys to hash table, map, JSON etc

type magic....

....toList [("Commands.Hello","Print greeting"),
                ("Commands.Goodbye","Say goodbye"),
                ("Commands.Hello.myflag", "it works!)]

I like this in that it would use your elegant type-level design but separate the "help data". Thoughts?

[lwdye]

As a workaround I can specify the program description as follows

let infomods = briefDesc <> fullDesc <> header ("myprogram - acme missile control")
                              <> footer API.copyright <> progDescDoc (Just API.progDescDoc)
let prefsmods = showHelpOnEmpty <> showHelpOnError
command<- getRecordWith infomods prefsmods

If I could suppress "Available commands:" section. This would be sufficient. Also it is redundant as it stands now since

Usage: myprogram (create | update | send | missiles )
Available options:
  -h,--help                Show this help text
Available commands:
  create                                   
  update                   
  send                    
  missiles              

doesn't give any additional information. Perhaps just dropping "Available commands" is a good idea in any case or perhaps the case a program description is supplied with showHelpOnEmpty. Thoughts?

[lwdye]

Related is that given -h is supported on

myprogram -h

how can we specify other flags at top level?

[Gabriella439]

So there actually is an intermediate solution in between optparse-applicative and optparse-generic, which is the TurtleOptions module:

https://hackage.haskell.org/package/turtle-1.4.3/docs/Turtle-Options.html

For example, it has a subcommandGroup function which is similar to what you just described:

https://hackage.haskell.org/package/turtle-1.4.3/docs/Turtle-Options.html#v:subcommandGroup