25 Mar
2009
25 Mar
'09
5:32 p.m.
On Wed, 25 Mar 2009, Jonathan Cast wrote:
On Wed, 2009-03-25 at 07:39 -0400, Xiao-Yong Jin wrote:
Could you elaborate more about why this kind of breakage wouldn't happen if 'try' is used in an IO monad as intended?
It would. But it would happen in IO, which is allowed to be non-deterministic. Pure Haskell is not allowed to be non-deterministic.
In my opinion, 'try' catching 'error's is still a hack, since 'error's aka bottom mean programming error. Thus catching them is debugging, bug hiding or something worse, but not exception handling. 'try' and friends should be limited to exceptional outcomes of IO actions, e.g. "disk full", "file read protected" etc. There might be a variant 'unsafeTry' which can also block 'error's.