[mafribe]

    write bad code [...] which 
    you will later throw away

Implementing a quick & dirty prototype, throwing it away and reimplementing it from scratch is not such a bad software engineering techique: first time to understand the problem, second time to make the implementation nice.

A lot of bad software comes from not throwing the prototype away, but insteat trying to refine it into a product. Result = spaghetti.

[hashhar]

I agree. I got into the practice after I picked up F#. I used to create simple solutions in the interactive REPL as mainly proof of concepts. Once I had the basics down, I sat down and wrote a list of possible edge cases, expected user inputs, the format of output and the command line interface for the tool. Then I started coding from scratch and had a good and clean working solution ready. Helped me a lot.