[Haskell-cafe] Propositional logic implementation

[Miguel Mitrofanov]

Look at SYB (Data.Data, Data.Generics.*). For example, your "symbols"  
function can be rewritten as

symbols :: Sentence -> [Symbol]
symbols s = nub $ listify (const True) s

"true" is not that simple, because this code is NOT boilerplate - each  
alternative is valuable by itself.

On 10 Jan 2009, at 23:56, Andrew Wagner wrote:

> All,
> Is there some better way to do this? It seems like a lot of  
> boilerplate. Thanks!
>
> http://hpaste.org/13807#a1
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