exact-pi 0.2.0.0 → 0.2.1.0

raw patch · 3 files changed

+47/−4 lines, 3 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• changelog.md +12/−0
• exact-pi.cabal +3/−3
• src/Data/ExactPi.hs +32/−1

@@ -0,0 +1,12 @@+0.2.1.0
+-------
+* Added support for converting to exact integers or exact rationals.
+
+0.2.0.0
+-------
+* Removed dependency on groups package, since it appears not to be widely used.
+* Fixed a missing case alternative in recip.
+
+0.1.2.0
+-------
+* Added support for GHC 7.8.

@@ -2,7 +2,7 @@ -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                exact-pi
-version:             0.2.0.0
+version:             0.2.1.0
 synopsis:            Exact rational multiples of pi (and integer powers of pi)
 description:         Provides an exact representation for rational multiples of pi alongside an approximate representation of all reals.
                      Useful for storing and computing with conversion factors between physical units.
@@ -14,7 +14,8 @@ -- copyright:           
 category:            Data
 build-type:          Simple
-extra-source-files:  README.md
+extra-source-files:  README.md,
+                     changelog.md
 cabal-version:       >=1.10
 
 library
@@ -29,4 +30,3 @@ source-repository head
   type:                git
   location:            https://github.com/dmcclean/exact-pi.git
-  

@@ -19,12 +19,18 @@ (
   ExactPi(..),
   approximateValue,
+  isZero,
   isExactZero,
-  isExactOne
+  isExactOne,
+  isExactInteger,
+  toExactInteger,
+  isExactRational,
+  toExactRational
 )
 where
 
 import Data.Monoid
+import Data.Ratio (numerator, denominator)
 import Prelude
 
 -- | Represents an exact or approximate real value.
@@ -39,6 +45,11 @@ approximateValue (Exact z q) = (pi ^ z) * (fromRational q)
 approximateValue (Approximate x) = x
 
+-- | Identifies whether an 'ExactPi' is an exact or approximate representation of zero.
+isZero :: ExactPi -> Bool
+isZero (Exact _ 0) = True
+isZero (Approximate x) = x == (0 :: Double)
+
 -- | Identifies whether an 'ExactPi' is an exact representation of zero.
 isExactZero :: ExactPi -> Bool
 isExactZero (Exact _ 0) = True
@@ -48,6 +59,26 @@ isExactOne :: ExactPi -> Bool
 isExactOne (Exact 0 1) = True
 isExactOne _ = False
+
+-- | Identifies whether an 'ExactPi' is an exact representation of an integer.
+isExactInteger :: ExactPi -> Bool
+isExactInteger (Exact 0 q) | denominator q == 1 = True
+isExactInteger _                                = False
+
+-- | Converts an 'ExactPi' to an exact 'Integer' or 'Nothing'.
+toExactInteger :: ExactPi -> Maybe Integer
+toExactInteger (Exact 0 q) | denominator q == 1 = Just $ numerator q
+toExactInteger _                                = Nothing
+
+-- | Identifies whether an 'ExactPi' is an exact representation of a rational.
+isExactRational :: ExactPi -> Bool
+isExactRational (Exact 0 _) = True
+isExactRational _           = False
+
+-- | Converts an 'ExactPi' to an exact 'Rational' or 'Nothing'.
+toExactRational :: ExactPi -> Maybe Rational
+toExactRational (Exact 0 q) = Just q
+toExactRational _           = Nothing
 
 instance Show ExactPi where
   show (Exact z q) | z == 0 = "Exactly " ++ show q