[Haskell-cafe] convert a list of booleans into Word*

[Paul.Brauner at loria.fr]

Thanks for the answers. I already had a look at Binary but, as said
above, it doesn't support bit manipulation, only bytes.



On Wed, Sep 30, 2009 at 11:18:03AM +0200, Paul.Brauner at loria.fr wrote:
> Hello,
> 
> I haven't found a function in hackage or in the standard library that
> takes a list of booleans (or a list of 0s and 1s, or a tuple of booleans
> or 0s and 1s) and outputs a Word8 or Word32.
> 
> I have written one which seems very inefficient :
> 
> toWord8 :: [Bool] -> Word8
> toWord8 bs = go 0 0 bs
>   where go n r []     = r
>         go n r (b:bs) = go (n+1) (if b then setBit r n else clearBit r n) bs
> 
> Is there a better way to do this out there ?
> 
> (If it helps, i'm writting a toy compression algorithm, which outputs
> binary as lists of booleans, and I'd like to output that in a file).
> 
> Cheers
> Paul
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