[Haskell-cafe] better error message for "undefined"
Martijn van Steenbergen
martijn at van.steenbergen.nl
Thu Sep 10 08:08:48 EDT 2009
You can use the error function. It accepts a string that is displayed
when the error is evaluated:
> GHCi, version 6.10.1: http://www.haskell.org/ghc/ :? for help
> Loading package ghc-prim ... linking ... done.
> Loading package integer ... linking ... done.
> Loading package base ... linking ... done.
> Prelude> error "hi!"
> *** Exception: hi!
Andrew U. Frank wrote:
> is there a way to have different kinds of undefined? such that i get a message
> which one was hit. something like writing in the code 'unefined 'my error 123'
> which prints 'undefined - my error 123' when it is accidentally hit.
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