[Yhc] Yhc: A first impression

[Thorkil Naur]

Hello,

On Saturday 06 January 2007 12:47, Neil Mitchell wrote:
> ...
> > 6. I get the message "Nothing derived for Id 424 at nopos" and similar
> > messages with 424 replaced by other numbers when a number of modules are
> > compiled. The modules seem to compile OK, however. What does this mean?
> 
> Never seen that before. Can you attach a module that gives this behaviour?

Here is one, very small so I refrain from attaching:

module Id424 where
  f x = xd2 where (xd2,0) = x`divMod`2

This is what it looks like when I compile it:

Thorkil-Naurs-Computer:~/tn/test/Yhc/Id424 thorkilnaur$ yhc Id424
Compiling Id424            ( Id424.hs )
Nothing derived for Id 207 at nopos
Thorkil-Naurs-Computer:~/tn/test/Yhc/Id424 thorkilnaur$

Bytecode is produced.

> ...
> > 9. Finally, I get a message "Error: Identifier getArgs used at 67:15-67:21 
is
> > not defined." when using that function in a Main module:
> >
> >   args<-getArgs
> 
> Have you got import System.Environment? or import System? It's
> possible that one of them is lacking a reexport of getArgs. I've
> certainly used getArgs in a Yhc program before.
> 

I had import System. Changing to import System.Environment removed the 
complaint. Thanks.

> ... This has been very helpful!

Very satisfying, thanks.

Best regards
Thorkil