Knowing whether a computation will terminate is in general the halting problem, so immediately you're looking at a syntactic restriction. Here the only ones I can think of are artificial at best (i.e., they don't work for examples more than what you've shown here):
http://trac.haskell.org/haskell-platform/ticket/180 There was some discussion [1] on putting a limit to what the interpreter prints out. Off the top of my head I suppose a hacky way to do this would be to define a new type deriving show in a way that printed out the list to some bounded depth. Kris [1] http://projects.haskell.org/pipermail/haskell-platform/2011-July/001619.html On Tue, Jul 23, 2013 at 10:30 PM, yi lu <zhiwudazhanjiang...@gmail.com> wrote: > I am wondering how can I ask ghci to show an infinite list wisely. > When I type > > fst ([1..],[1..10]) > > The result is what as you may guess > > 1,2,3,4,...(continues to show, cut now) > > How could I may ghci show > > [1..] > > this wise way not the long long long list itself? > > Yi > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe