New option type `form`

[martinklepsch]

Some tasks allow you to pass edn forms for evaluation. On the CLI you can pass those as string and we'll read-string them. If you pass a form in a string in Clojure code it will be interpreted as a string essentially resulting in a no-op. See #666 for details.

To prevent users from running into this issue a warning has been added in #666 but this only covers the :eval option of the repl task leaving any other edn options that expect forms as-is.

I think ideally there would be a specific type for options that expect forms (~= function invocations) to distinguish the case of passing data vs. passing a Clojure form.

The Task Options DSL wiki page also mentions a code type but that implies evaluation of the form. As I understand this is most often used to pass symbols?

Preliminary todo list:

• [ ] extend boot.cli/parse-atom by a form option:

    form  (fnil read-string "nil")

• [ ] extend boot.cli/assert-atom by a form option:

    form  list?

• [ ] update docs on Task Options DSL wiki page

Tasks affected

• repl :eval

[SevereOverfl0w]

It seems that it would be just as appropriate in cases for a form to be valid as a constant also. For example if I want to use a pre-calculated value from a required namespace. Of course, the workaround is (constantly "foo"), but it seems like a needless restriction.