14 Jun
2008
14 Jun
'08
4:29 p.m.
Hi
How 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 * impossible - the programmer knows this can't occur * abort - deliberate aborting because the user made some mistake. The safe library provides abort already. Thanks Neil