[Haskell-cafe] Ensuring all values of an ADT are explicitly handled OR finding all occurrences of type X in my app

Michael Orlitzky michael at orlitzky.com
Tue Jan 31 04:19:57 UTC 2017

On 01/30/2017 09:47 PM, Saurabh Nanda wrote:
> Hi,
> If I have the following ADT
> data BookingState = Confirmed | Cancelled
> which had a very high chance of being expanded in the future to have more
> values. How do I ensure that every pattern match on BookingState matches
> each value explicitly. Basically prevent the '_' matcher ?

Don't write the "_" case? GHC will warn you about any pattern matches
you've missed.

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