combined flags

[BebeSparkelSparkel]

Allow combined flags like with ls

ls [-1AaCcdFfgHhikLlmnopqRrSsTtux] [file ...]

Some questions that need answering.

• Is this an anti-pattern, and should it be implemented?
• Should this be limited to single letter flags?
• How should it be implemented?
  • combine flags at the type level and then split the flags on parsing

[SamuelSchlesinger]

I'm not sure of how I feel about this. If it can be implemented clearly and well-documented, the more features the better, but if it adds confusion or indirection to the extant code, I will be anti.

[BebeSparkelSparkel]

This is a tricky one. I don't really like learning them but as a power user they are very helpful.

[SamuelSchlesinger]

Agreed, sadly I think this issue is especially important despite the pain it will likely cause in the implementation.

[BebeSparkelSparkel]

Perhaps this isn't as hard you think. This could be implemented as:

data Flags
  :: Symbol -- prefix
  -> Symbol -- single letter flags
  -> *

then run would

• match on the prefix
• ensure all letters are in the single letter flags symbol
• split the letters and prepend the prefix and then prepend those on the State
• the following flag handlers will then consume the indiv

Another option would be:

data Flags
  :: Symbol -- prefix
  -> [(Symbol,Symbol)] -- single letter map to flag
  -> *

this is a bit more flexible than the previous option that allows for mappings to flags that have more than one letter and allows for a different prefix for combined single letters flags than the other flags.

As for checking this it may be possible for a type function to ensure that there is a flag handler is defined after this.