sorting failed error

[bearophile]

maarten van damme:

> I really dislike contracts, they kind off blow your function up 
> while adding not that much. I'll add some unit tests.

They make your programs more robust. Contracts are used to spot 
bugs in your code and not to validate data coming from the 
"outside world".

As most other tools there are few ways to use them well, and many 
ways to use them badly. I suggest you to read about the meaning 
of Contract programming, so maybe you will learn to appreciate 
them.

Bye,
bearophile