[Haskell-cafe] Identity of indiscernibles (Was: Alternative name for return)

Tom Ellis:

If I were writing a Haskell compiler I could certainly define 'IO' to be a datatype that would allow me to compare 'putStr "c"' to itself. The comparison could not be of operational equivalence, but it would still be possible to compare values in IO in a reasonable sense.

Would you add to all this: getLine == getLine etc.? Good luck! I suspect that you would have to establish also the equality relation between functions and between infinite streams. And you would end as Giordano Bruno and Jeanne d'Arc. But for different reasons. Jerzy Karczmarczuk