Interactive IO anomaly with GHC 5.04, OS X

[Peter Pudney]

If I start GHCi  (OS X v10.1.5) and type in the following interactive function,
it works as expected:

	Prelude> do {putStr "Prompt: "; l <- getLine; putStrLn l}
Prompt: OK
OK
But if I load a module, even the empty module

>  module Empty where

the prompt is not written until after the getLine:

	Prelude> :l Empty
Compiling Empty            ( /Users/pjp/documents/Haskell/Empty.lhs, interpreted
)
Ok, modules loaded: Empty.
*Empty> do {putStr "Prompt: "; l <- getLine; putStrLn l}
wrong!
Prompt: wrong!
However, if I output a newline character at the end of the prompt, it works as
expected:

	*Empty> do {putStrLn "Prompt: "; l <- getLine; putStrLn l}
Prompt: 
OK
OK

	*Empty> do {putStr "Prompt:\n..."; l <- getLine; putStrLn l}
Prompt:
wrong
...wrong
Unloading the module does not help -- I have to restart GHCi  to get the
correct behaviour.

Compiled scripts exhibit the incorrect behaviour.



Peter