[Haskell-cafe] First steps in Haskell

[Wolfgang Jeltsch]

Am Sonntag, 18. Dezember 2005 17:42 schrieb Daniel Carrera:
> Lemmih wrote:
> > GHC is a compiler. If you want to compile to a binary then you must
> > define a function called 'main'. Otherwise just load the file in ghci
> > (`ghci fac.hs`).
>
> I would expect GHC to be able to compile a program with a function that
> is not called 'main'. I wouldn't expect it to print anything when run,
> but I would expect it to compile.

So you want a program that doesn't contain a main variable to be compiled into 
an executable which does nothing?  This doesn't seem to make much sense. 

In addition, Haskells requirement of a main variable is nothing new.  Take C, 
C++, Java, PASCAL.  They all require you to somehow specify a main 
program/function/method.

> `ghci fac.hs` doesn't give any errors. I don't understand why loading
> the file like that is ok but typing the entries is not.

Because the interactive environments are about evaluating expressions based on 
declarations which were made in Haskell source files, not about creating new 
declarations.  Expressions and declarations are just two different things.  I 
think, Cale explained why it might be a bad idea to allow entering 
declarations at the command line.

> This might be a problem for people exporing the language.

Hmm, don't know.

> Best,
> Daniel.

Best wishes,
Wolfgang