[arch-haskell] Cmdargs and common flags

Magnus Therning magnus at therning.org
Thu Jan 20 09:48:35 CET 2011

I'm looking for a good way of dealing with common flags in cmdargs.
Currently what I do requires a bit of repetition that I'd really like
to get rid of:

1. Data types

    data Modes = Cmd1 { foo :: String, ... } | Cmd2 { foo :: String, ... }

2. Mode specifications

    cmd1 = Cmd1 { foo = def &= help "..", ...}
    cmd2 = Cmd2 { foo = def &= help "..", ...}

I have no idea how to deal with the repetition in the data types, so
all suggestions are welcome.

For the repetition in the mode specifications I attempted to factor
the common bits into a "variable":

    flagFoo = "" &= help ".."

but that resulted in only the first command getting the proper
specification.  I suppose this comes down to the impurity, but how do
I work around that?  (Especially, are there any good examples of using
the pure part of the API?)


Magnus Therning                      OpenPGP: 0xAB4DFBA4
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