[Haskell-cafe] let and fixed point operator

[Andrew Coppin]

Brent Yorgey wrote:
>
>
>     It's really maddening to write 50,000 lines of code, eventually get it
>     to compile, run it, and have the program lock up and start
>     consuming so
>     much virtual memory that the entire PC becomes unstable within
>     seconds.
>
>     (This isn't helped by the fact that Ctrl+C doesn't seem to make
>     either
>     GHCi or GHC-compiled programs halt...) Now you have 50,000 lines of
>     otherwise untested code, and there's a bug within it
>     *somewhere*... good
>     luck.
>
>
> Well, this is why you should test your program in bits and pieces 
> before you get to that point.  Writing 50,000 LOC before you even run 
> your first test is a horrible idea in any programming language.

Horrible? Yes.

Avoidable? Not always, sadly...

(NB. 50,000 is an exaggeration. I've never written a program that large 
in my entire life in any programming language I've ever used.)

The problem is that, depending on the program, sometimes you have to 
write quite a lot of infrastructure before you get to the point where 
there's anything finished enough to test. Obviously it's better to avoid 
that happening, but that's easier said then done!