[Haskell-cafe] Maintaining laziness

[Jake McArthur]

Henning Thielemann wrote:
> I found it especially enlightening, that one can avoid a 'force' 
> function in a lazy parser by making the possibility of a parser failure 
> explicit in its type. I.e. a parser that cannot fail, need no 'force'. 
> (I learnt that in polyparse the 'force' function is hidden in 'apply':


I'm curious, what is the difference between using a force function and 
using lazy pattern matching?

- Jake