Add Never type to Prelude (WIP on warning for expressions after a function with return type Never) #3047
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The Never type can't be constructed so it can represent functions that never return. Spooky!
lpil
reviewed
Apr 27, 2024
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Hello! Thank you but it cannot be implemented as a named type as it has different semantics to them. It needs to be a super type of all other types, otherwise panic would be too restrictive and not usable in case expressions.
It's probably worth writing down what the design is before implementation as it'll be quicker to iterate on how it works that way. This will be the most complex change to the type system in some time.
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I see... then I guess I will just mark this as a draft for now and wait until a final design has been decided on. (This PR can also just be closed if it is taking up space) |
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Closing due to inactivity. Please feel free to reopen! Thank you |
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As discussed in #3044 it would be neat to add a type to the Prelude which could represent functions which never return.
The
Nevertype can not be constructed because if it could be constructed then someone could write a function which does return at some point with it.For example we don't want this to be possible:
WIP on figuring out where to add in the Warning for expressions coming after a function/expression of type
Never.