Question

One code work from runghc, but I can not compile same one with ghc command. Why?

Below is my minimal code and environment:
https://gist.github.com/1588756

Works well:

$ runghc cat.hs

Can not compile:

$ ghc cat.hs -o cat

Macbook air, max os x snow leopard

Answer 1

The .cs extension shown in your paste is wrong;¹ rename the file to cat.hs and it’ll work fine.

This error message:

ld: warning: ignoring file cat.cs, file was built for unsupported file format
which is not the architecture being linked (i386)

occurs when you pass a file GHC doesn’t know how to handle; it just passes it on directly to the linker, which then ignores it as it doesn’t know, either. 🙂

¹ At least until GHC gets C# support…