Comments (2)
A slightly simpler example:
data State = On | Off deriving (Data, Show, Typeable)
data Mode = Mode {state :: [State]} deriving (Show, Data, Typeable)
main = print =<< cmdArgs Mode{state = enum [[On], [Off]]}
And the smallest change that can fix it:
main = print =<< cmdArgs Mode{state = enum [[On] &= name "on", [Off] &= name "off"]}
So the problem is that enum
tries to guess at flag names based on the value in each of [On]
and [Off]
. It can guess the value from a constructor, but not a list. Since it can't guess the name it raises an exception. The ways round this are:
- Make it guess a name by peeking inside the list. That works for my revised example, and might work for your original example or not (not sure if it looks at
ignore
first or not) - but it should be doable in this case. However, it's not going to be possible in all cases. - Improve the error message, so it's clear what went wrong and how to fix it.
from cmdargs.
Tested by adding name
to the non-ignored flags in my example and it does work properly without needing to name an ignored argument.
from cmdargs.
Related Issues (20)
- expandArgsAt doesn't understand ~ HOT 1
- modeHelp eats blank lines HOT 1
- Generate help text if no default mode was specified HOT 2
- Wondering how to make a required argument. HOT 4
- A problem with common flags and multiple typFile resulting in "ITEM" HOT 4
- sudo-like cli: a way to instruct `cmdargs` to not look for flags in the remaining arguments HOT 2
- man and info generation
- Using `&= help` with `&= argPos` throws an error HOT 1
- Comments in args file HOT 5
- Default Lists?
- Running multiple sub-commands HOT 1
- Inconsistency in handling boolean arguments HOT 1
- Way to use multiple modes without partial record field selectors? HOT 2
- Tighter bounds base for old cmdargs HOT 1
- Is it possible to create arguments with only a single dash? HOT 1
- hidden arguments? HOT 6
- splitArgs: document quoting rules
- How can I customize --numeric-version? HOT 13
- Incorrect handling of subcommands with the same argument HOT 1
- ghc-9.6.1 runtime error HOT 1
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from cmdargs.