Cool! Are you considering argument validation support?

@UE21H2HHD Do you have any ideas on what that might look like?

Pseudo-code is welcome

Like:

{:validate {:foo #{:foo :bar}}

Sorry, had not given it much thought, but I do seem to like a cli that validates args and provides usage help.

The philosophy behind babashka CLI is that you would turn a function into a CLI. If you validate args when doing a CLI invocation, why should this validate and not when you invoke the function from a REPL?

Isn't CLI just a special case of a more general fn invocation?

You can use :pre in the function to support both

I'm just echoing one argument here, please change my mind, I'm curious to hear your thoughts

Ya, that's certainly a reasonable argument. I do like a consistent way of validating args and presenting usage help. I currently often use docopt these days, it is not perfect (I sometimes spin my wheels figuring out how to express things) but it helps with these goals.

Maybe I'm focusing on classic command line usage/validation/help. This might not be something babashka-cli wants to concern itself with.

yeah, I think it's what people expect and adding a :validate thing seems reasonable

Maybe provide a helper to format malli schema validation errors in a "CLI appropriate form"?

separate the parsing of flags to a map with displaying errors if that map aint good

@U3JH98J4R bb CLI has no dependency on malli / spec / schema

But just throwing an error with a configurable message upon the first failure seems reasonable

Maybe look at how tools.cli does this

:validate [#(< 0 % 0x10000) "Must be a number between 0 and 65536"]]

:validate [#(< 0 % 0x10000) #(str % " is not a number between 0 and 65536")]

instead of a tuple, we could have :validate be a function which receives a map

:validate {:fn #{:foo :bar} :error-fn (fn [{:keys [opt]}] {:message (str "O no!!!! opt")}) 

But it seems you could do this fairly easily yourself after the options have been passed to the function

I don't understand why you would only throw on CLI invocation but give fn invocation from the REPL a free pass

But I'm still open to feedback, haven't made up my mind on this 100%

I guess you could say something similar for :closed and :required

I guess parse-args can return :errors thing, like tools.cli does: If the validation-fn returns a falsey value, the validation-msg is added to the errors vector.

I thinking it might be a matter of usage perspective. If as a user you know you are using babashka-cli as a way to invoke a Clojure function from the command line, you might be just fine with a stack trace as an error, and then having to look at a docstring and/or source for proper usage. If as a user you see yourself as using a command line tool, you expectations will likely be different. The Clojure fn being called is an implementation detail. You likely expect some --help or help option to be available, and likely expect textual error and/or usage help when you specify invalid input. When I write babashka tasks, I see myself as writing command line tools, so I (usually) try to make them follow the general conventions of command line tools.

I agree, just thinking of what library would make it easy to do that

So it's a disjoint task, I don't think babashka needs to support it so much as "map->CLI conventions" is a task people will want to do

I'm ok with adding some validation, ideas welcome of course

the bb -x foo/bar --dude case should then also handle the :errors if there are some, print those and exit with 1

posted an idea here: https://github.com/babashka/cli/issues/31

I'm open to a PR for this

@U04VDKC4G Let's go to #babashka-cli

I replied over there