On Sat, Jul 31, 2010 at 4:56 PM, michael rice <nowg...@yahoo.com> wrote: > > From: http://en.wikibooks.org/wiki/Haskell/Laziness > > > Given two functions of one parameter, f and g, we say f is stricter than g if > f x evaluates x to a deeper level than g x > > Exercises > > 1. Which is the stricter function? > > f x = length [head x] > g x = length (tail x) > > > > Prelude> let f x = length [head x] > Prelude> let g x = length (tail x) > Prelude> f undefined > 1 > Prelude> g undefined > *** Exception: Prelude.undefined > Prelude> > > > > So, g is stricter than f? > > Wouldn't both functions need to evaluate x to the same level, *thunk* : > *thunk* to insure listhood? > > f x = length [head *thunk* : *thunk*] > g x = length (tail *thunk* : *thunk*) > > Michael > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >
Notice the two different kinds of brackets being used in f versus g :) _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe