On Sat, 14 Jun 2008, Neil Mitchell wrote:
HiHow about a {-# IMPOSSIBLE #-} pragma that documents the fact that a particular point in the program *should* be unreachable?Why not make it a function taking a string and returning a value of any type. Then we can keep our language and not break various parsing/type checking properties and rules on pragmas. We can even define it: impossible = error Now you can use tools like Catch and Reach to ensure it is impossible. I think it would be nice to distinguish between: * error - inserted by the compiler
Example?
* impossible - the programmer knows this can't occur
This is an error. However the programmer adds a message because he might be wrong.
* abort - deliberate aborting because the user made some mistake.
This is an exception. The signature of a function must reflect this by a Maybe, Either type etc.
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