| Portability | Haskell98 + CPP + GeneralizedNewtypeDeriving |
|---|---|
| Stability | provisional |
| Maintainer | wren@community.haskell.org |
| Safe Haskell | Trustworthy |
Data.Number.CalkinWilf
Description
Enumerate the rationals in Calkin--Wilf order.
- Jeremy Gibbons, David Lester, and Richard Bird (2006). Enumerating the Rationals. JFP 16(3):281--291. DOI:10.1017/S0956796806005880 http://www.cs.ox.ac.uk/jeremy.gibbons/publications/rationals.pdf
- newtype CalkinWilf a = CalkinWilf (Ratio a)
- unCalkinWilf :: CalkinWilf a -> Ratio a
Documentation
newtype CalkinWilf a Source
Enumerate the rationals in Calkin--Wilf order. The enumeration is symmetric about zero, ensuring that all the negative rationals come before zero and all the positive rationals come after zero.
BUG: while the succeeds, precedes, toEnum, and fromEnum
methods are correct, they are horribly inefficient. This can be
rectified (or at least mitigated), but this remains to be done.
Constructors
| CalkinWilf (Ratio a) |
Instances
| Integral a => Enum (CalkinWilf a) | |
| Eq a => Eq (CalkinWilf a) | |
| Integral a => Fractional (CalkinWilf a) | |
| Integral a => Num (CalkinWilf a) | |
| Integral a => Ord (CalkinWilf a) | |
| (Integral a, Read a) => Read (CalkinWilf a) | |
| Integral a => Real (CalkinWilf a) | |
| Integral a => RealFrac (CalkinWilf a) | |
| (Integral a, Show a) => Show (CalkinWilf a) | |
| Integral a => Enum (CalkinWilf a) | |
| Integral a => DownwardEnum (CalkinWilf a) | |
| Integral a => UpwardEnum (CalkinWilf a) |
unCalkinWilf :: CalkinWilf a -> Ratio aSource