[Haskell-beginners] Compiling

Daniel Fischer daniel.is.fischer at web.de
Fri Jun 25 01:04:54 EDT 2010

On Friday 25 June 2010 06:50:06, Chris Saunders wrote:
> I have just started trying to learn Haskell again (I seem to have a
> mental block against this language).  Right now I'm using Haskell in 5
> steps.  I have created the file hello.hs exactly as in the section
> "Write your first Haskell program".  I then opened a cmd (I'm using
> Windows) window in the directory where I created hello.hs and entered
> "ghc -o hello hello.hs".

The matter with upper/lower case has already been treated, so I'll focus on 
the command line.

Unless you know exactly that you can't use the --make option and why, 
always compile with

ghc --make [other options if wanted] file[s]

without --make, you'll get some puzzling 'undefined symbol' messages from 
the linker sooner rather than later.

> What follows is the output of the cmd window:
> hello.hs:1:7: Not in scope: data constructor `PutStrLn'
> Can someone tell me why I am having this problem?
> Regards
> Chris Saunders

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