[Haskell-cafe] Trying to Express Constraints using a data structure

2009-05-18 Thread GüŸnther Schmidt
Hi all, I'm trying to express a constraint using a data structure. Let's say I'd want to express a mapping of a to b, c to b, d to b and e to f. A mapping can also be from a to a, b to b and so on. The constraint is that one cannot map a to b if b was already mapped to let's say c. I'd

Re: [Haskell-cafe] Trying to Express Constraints using a data structure

2009-05-18 Thread Steffen Schuldenzucker
On 16:25 Mon 18 May , Gü?nther Schmidt wrote: Hi all, I'm trying to express a constraint using a data structure. Let's say I'd want to express a mapping of a to b, c to b, d to b and e to f. A mapping can also be from a to a, b to b and so on. The constraint is that one cannot map a