env-parser

@env-parser is a small library for configuring programs based on information from the environment. It's goals and design are similar to that of @cmdargs@ or @optparse-applicative@ but aimed at automatically managed programs such as those that might be run via Heroku or Runit/daemontools. @env-parser@ intentionally sacrifices power for comprehensibility---the primary interface, @Parser@, implements only @Applicative@. This provides better runtime error messages and automatically generated static help using parser annotations. It also expresses a principle of simplicity in configuration: arbitrary uses of @Monad@ or even @Alternative@ can lead to opaque failures prior to a program even beginning to run.