Added nan, isNaN, infinity, isFinite

Author: sharkdp

src/Data/Number.purs

@@ -1,6 +1,10 @@
 -- | A module for working with PureScripts builtin `Number` type.
 module Data.Number
   ( Fraction
+  , nan
+  , isNaN
+  , infinity
+  , isFinite
   , fromString
   , eqRelative
   , eqApproximate
@@ -16,8 +20,23 @@ import Prelude
 
 import Data.Maybe (Maybe(..))
 import Math (abs)
-import Global (readFloat, isFinite)
+import Global as G
 
+-- | Not a number (NaN).
+nan ∷ Number
+nan = G.nan
+
+-- | Test whether a `Number` is NaN.
+isNaN ∷ Number → Boolean
+isNaN = G.isNaN
+
+-- | Positive infinity.
+infinity ∷ Number
+infinity = G.infinity
+
+-- | Test whether a number is finite.
+isFinite ∷ Number → Boolean
+isFinite = G.isFinite
 
 -- | Attempt to parse a `Number` from a `String` using JavaScripts
 -- | `parseFloat`. Returns `Nothing` if the parse fails or if the result is not
@@ -41,12 +60,11 @@ import Global (readFloat, isFinite)
 -- | Nothing
 -- | ```
 fromString ∷ String → Maybe Number
-fromString = readFloat >>> check
+fromString = G.readFloat >>> check
   where
     check num | isFinite num = Just num
               | otherwise    = Nothing
 
-
 -- | A type alias for (small) numbers, typically in the range *[0:1]*.
 type Fraction = Number
 

test/Main.purs

@@ -3,7 +3,8 @@ module Test.Main where
 import Prelude
 
 import Data.Maybe (Maybe(..), fromMaybe)
-import Data.Number (eqRelative, eqAbsolute, fromString, (≅), (≇))
+import Data.Number (nan, isNaN, infinity, isFinite, eqRelative, eqAbsolute,
+                    fromString, (≅), (≇))
 
 import Control.Monad.Aff.AVar (AVAR)
 import Control.Monad.Eff (Eff)
@@ -120,6 +121,21 @@ main = runTest do
         0.1 + 0.200001 ≇ 0.3
 
 
+  suite "isNaN" do
+    test "Check for NaN" do
+      assert "NaN is not a number" $ isNaN nan
+      assertFalse "infinity is a number" $ isNaN infinity
+      assertFalse "1.0 is a number" $ isNaN 1.0
+
+
+  suite "isFinite" do
+    test "Check for infinity" do
+      assert "1.0e100 is a finite number" $ isFinite 1.0e100
+      assertFalse "detect positive infinity" $ isFinite infinity
+      assertFalse "detect negative infinity" $ isFinite (-infinity)
+      assertFalse "detect NaN" $ isFinite nan
+
+
   suite "fromString" do
     test "valid number string" do
       assert "integer strings are coerced" $