Disambiguation

It is possible to configure optparse-applicative to perform automatic disambiguation of prefixes of long options. For example, given a program foo with options --filename and --filler, typing

$ foo --fil test.txt

fails, whereas typing

$ foo --file test.txt

succeeds, and correctly identifies "file" as an unambiguous prefix of the filename option.

Option disambiguation is off by default. To enable it, provide the disambiguate modifier to the prefs builder, and pass the resulting preferences to one of the parser runners that take an ParserPrefs parameter, like customExecParser.

Here is a minimal example:

import Options.Applicative

sample :: Parser ()
sample = () <$
  switch (long "filename") <*
  switch (long "filler")

main :: IO ()
main = customExecParser p opts
  where
    opts = info (helper <*> sample) idm
    p = prefs disambiguate