Am 29/05/2012 14:20, schrieb Lawrence Paulson:
> I am marking some student work submitted for the Cambridge Isabelle course, 
> and have seen some examples where students have gone terribly wrong because 
> they overlooked the warning “Ignoring redundant equation" in a function 
> definition. This sort of mistake could happen to anybody, and it means that 
> proofs are being undertaken on the basis of a mistaken definition. Somebody 
> reading the theory could also overlook this mistake, which goes against the 
> idea that structured proofs should be readable without being executed.
> 
> I propose that this particular warning should become a fatal error.

Sounds reasonable.

Tobias

> Warnings are appropriate for situations that are difficult to avoid, such as 
> overlapping patterns. They might be appropriate for situations that are 
> common and generally harmless, such as missing patterns. But entirely 
> superfluous equations should be seen as a fatal error. This should be a very 
> easy change to implement.
> 
> Larry
> 
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