#9816: Add function for size-checked conversion of Integral types -------------------------------------+------------------------------------- Reporter: spl | Owner: Type: feature | Status: patch request | Milestone: Priority: normal | Version: 7.9 Component: Core | Keywords: Libraries | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: D512 | -------------------------------------+------------------------------------- Description changed by spl: Old description:
Based on the discussion in [http://thread.gmane.org/gmane.comp.lang.haskell.libraries/23338 this thread], I would like to add a function to the {{{base}}} library that is similar to {{{fromIntegral}}} but only successful if the argument fits in the result type.
If possible, I would like to get this into 7.10. My apologies for running late on it. Hopefully, since it is a relatively small change overall, the "only" controversy will be bikeshedding.
I have concluded that adding @hvr's {{{intCastMaybe}}} from [http://hackage.haskell.org/package/int-cast int-cast] is the best possible option. Previously, I thought a {{{Bounded}}}-based version was also useful; however, I realized that it did not deal properly with conversions like {{{Int<->Word}}}/{{{Int8<->Word8}}}/etc. as well as {{{intCastMaybe}}} and would need specialized versions that {{{intCastMaybe}}} provides automatically.
New description: Based on the discussion in [http://thread.gmane.org/gmane.comp.lang.haskell.libraries/23338 this thread], I would like to add a function to the {{{base}}} library that is similar to {{{fromIntegral}}} but only successful if the argument fits in the result type. If possible, I would like to get this into 7.10. My apologies for running late on it. Hopefully, since it is a relatively small change overall, the "only" controversy will be bikeshedding. I have concluded that adding @hvr's {{{intCastMaybe}}} from [http://hackage.haskell.org/package/int-cast int-cast] is the best possible option. Previously, I thought a {{{Bounded}}}-based version was also useful; however, I realized that it did not deal optimally with conversions like {{{Int<->Word}}}/{{{Int8<->Word8}}}/etc. as well as {{{intCastMaybe}}} does and would need specialized versions that {{{intCastMaybe}}} provides automatically. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9816#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler