How to set a program's command line arguments for GHCi?

Question

Suppose some Haskell file is executed with

runghc Queens.hs gecode_compile 

Now, this fails, and I want to debug it with ghci. How do I pass the option gecode_compile into the program, so getArgs will read it correctly?

Thanks!!

Answer 1

You can also set the command line arguments in ghci

ghci> :set args foo bar ghci> main 

or

ghci> :main foo bar 

Answer 2

You can use the System.Environment.withArgs function to execute main with your desired arguments.

Here's an example session (irrelevant details elided):

$ ghci GHCi, version 7.0.3: http://www.haskell.org/ghc/  :? for help Prelude> import System.Environment Prelude System.Environment> let main = getArgs >>= mapM_ putStrLn Prelude System.Environment> withArgs ["hello", "world"] main hello world