A year has passed and I have just discovered that you had exactly the same idea two years before me! http://augustss.blogspot.se/2014/04/haskell-error-reporting-with-locations_5... On Tue, Jun 21, 2016 at 01:45:13AM +0000, Augustsson, Lennart wrote:
It's totally compatible with Haskell semantics, since Haskell does not give any semantics to IO. Anything can happen when you do IO. But it's still a bit weird. :)
-----Original Message----- From: Haskell-Cafe [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Tom Ellis Sent: 20 June 2016 16:04 To: haskell-cafe@haskell.org Subject: [Haskell-cafe] Source code location in IO?
Is it compatible with the semantics of Haskell to have a function
sourceLocation :: IO String
which when run returns the source file location at which it is used? For example, suppose Main.hs is
module Main where
main = do putStrLn =<< sourceLocation putStrLn "Hello" putStrLn =<< sourceLocation
It would print the following when run
Main.hs:4 Hello Main.hs:6
and
module Main where
main = do let s = sourceLocation putStrLn =<< s putStrLn "Hello" putStrLn =<< s
It would print the following when run
Main.hs:4 Hello Main.hs:4
If this is not compatible with the semantics of Haskell, why not? I agree that the two programs must have the same denotation, but is there anything that requires them to have the same output when run?