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

I think the best solution here would be a new warning, say -fwarn-wildcard-patterns. This would be a simple syntactic check for a wildcard pattern anywhere in the module. Combined with -Werror you would be prevented from compiling programs with wildcards. I think this would be quite valuable given the rest of the comments in the thread, and probably a simple addition to GHC. Eric

On Jan 30, 2017, at 20:59, Saurabh Nanda wrote:

I would want the compiler (or linter) to help me here. Think if a mid-to-large team where everyone may not know (or remember) what the current best practices are.

On 31 Jan 2017 9:51 am, "Michael Orlitzky" wrote: 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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