Merge pull request #27 from purescript/lcg

Use Number type to avoid overflows in lcgNext
purescript · Jun 18, 2015 · 2dec9a7 · 2dec9a7
2 parents b4a3a03 + 61ce30f
commit 2dec9a7
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Showing 5 changed files with 16 additions and 3 deletions.
diff --git a/docs/Test/QuickCheck.md b/docs/Test/QuickCheck.md
@@ -100,6 +100,8 @@ instance showResult :: Show Result
 (<?>) :: Boolean -> String -> Result
 ```
 
+_left-associative / precedence -1_
+
 This operator attaches an error message to a failed test.
 
 For example:
@@ -114,6 +116,8 @@ test x = myProperty x <?> ("myProperty did not hold for " <> show x)
 (===) :: forall a b. (Eq a, Show a) => a -> a -> Result
 ```
 
+_left-associative / precedence -1_
+
 Self-documenting equality assertion
 
 #### `(/==)`
@@ -122,6 +126,8 @@ Self-documenting equality assertion
 (/==) :: forall a b. (Eq a, Show a) => a -> a -> Result
 ```
 
+_left-associative / precedence -1_
+
 Self-documenting inequality assertion
 
 
diff --git a/docs/Test/QuickCheck/Data/ApproxNumber.md b/docs/Test/QuickCheck/Data/ApproxNumber.md
@@ -29,4 +29,6 @@ instance numApproxNumber :: Num ApproxNumber
 (=~=) :: Number -> Number -> Boolean
 ```
 
+_left-associative / precedence -1_
+
 
diff --git a/docs/Test/QuickCheck/LCG.md b/docs/Test/QuickCheck/LCG.md
@@ -44,4 +44,6 @@ Step the linear congruential generator
 randomSeed :: forall e. Eff (random :: RANDOM | e) Seed
 ```
 
+Create a random seed
+
 
diff --git a/src/Test/QuickCheck.purs b/src/Test/QuickCheck.purs
@@ -46,14 +46,14 @@ quickCheck' n prop = do
   seed <- randomSeed
   let results = quickCheckPure seed n prop
   let successes = countSuccesses results
-  log $ show (toNumber successes) ++ "/" ++ show (toNumber n) ++ " test(s) passed."
+  log $ show successes ++ "/" ++ show n ++ " test(s) passed."
   throwOnFirstFailure one results
 
   where
 
   throwOnFirstFailure :: Int -> List Result -> QC Unit
   throwOnFirstFailure _ Nil = return unit
-  throwOnFirstFailure n (Cons (Failed msg) _) = throwException $ error $ "Test " ++ show (toNumber n) ++ " failed: \n" ++ msg
+  throwOnFirstFailure n (Cons (Failed msg) _) = throwException $ error $ "Test " ++ show n ++ " failed: \n" ++ msg
   throwOnFirstFailure n (Cons _ rest) = throwOnFirstFailure (n + one) rest
 
   countSuccesses :: List Result -> Int

diff --git a/src/Test/QuickCheck/LCG.purs b/src/Test/QuickCheck/LCG.purs
@@ -9,10 +9,12 @@ module Test.QuickCheck.LCG
 
 import Prelude
 
+import Math ((%))
 import Control.Monad.Eff (Eff())
 import Control.Monad.Eff.Random (RANDOM(), randomInt)
 import Data.Int (fromNumber, toNumber)
 import Data.Int.Bits (shl)
+import qualified Data.Maybe.Unsafe as U
 
 type Seed = Int
 
@@ -30,7 +32,8 @@ lcgN = one `shl` 30
 
 -- | Step the linear congruential generator
 lcgNext :: Int -> Int
-lcgNext n = (lcgM * n + lcgC) `mod` lcgN
+lcgNext n = U.fromJust $ fromNumber $ (toNumber lcgM * toNumber n + toNumber lcgC) % toNumber lcgN
 
+-- | Create a random seed
 randomSeed :: forall e. Eff (random :: RANDOM | e) Seed
 randomSeed = randomInt 0 lcgM