Specific integers

CHANGELOG.md

@@ -7,6 +7,7 @@ Notable changes to this project are documented in this file. The format is based
 Breaking changes:
 
 New features:
+- Added `minInt` and `maxInt` (#54 by @JamieBallingall)
 
 Bugfixes:
 

src/Data/Int.purs

@@ -1,5 +1,9 @@
+-- | Functions for working with PureScript's builtin `Int` type. A `Int`
+-- | is a signeed 32-bit integer.
 module Data.Int
-  ( fromNumber
+  ( minInt
+  , maxInt
+  , fromNumber
   , ceil
   , floor
   , trunc
@@ -31,6 +35,25 @@ import Data.Maybe (Maybe(..), fromMaybe)
 import Data.Number (isFinite)
 import Data.Number as Number
 
+-- | The most negative `Int`, equal to -2^31.
+-- | ```purs
+-- | > minInt
+-- | -2147483648
+-- | ```
+minInt :: Int
+minInt = -0x80000000
+
+-- | The most positive `Int`, equal to 2^31 - 1.
+-- | ```purs
+-- | > maxInt
+-- | 2147483647
+-- |
+-- | > maxInt + 1 == minInt
+-- | true
+-- | ```
+maxInt :: Int
+maxInt = 0x7FFFFFFF
+
 -- | Creates an `Int` from a `Number` value. The number must already be an
 -- | integer and fall within the valid range of values for the `Int` type
 -- | otherwise `Nothing` is returned.

test/Test/Data/Int.purs

@@ -2,7 +2,7 @@ module Test.Data.Int (testInt) where
 
 import Prelude
 
-import Data.Int (binary, ceil, even, floor, fromNumber, fromString, fromStringAs, hexadecimal, octal, odd, parity, pow, quot, radix, rem, round, toNumber, toStringAs)
+import Data.Int (binary, ceil, even, floor, fromNumber, fromString, fromStringAs, hexadecimal, maxInt, minInt, octal, odd, parity, pow, quot, radix, rem, round, toNumber, toStringAs)
 import Data.Maybe (Maybe(..), fromJust)
 import Effect (Effect)
 import Effect.Console (log)
@@ -13,6 +13,15 @@ import Test.Assert (assert)
 testInt :: Effect Unit
 testInt = do
 
+  log "minInt should be -2147483648"
+  assert $ minInt == -2147483648
+
+  log "maxInt should be 2147483647"
+  assert $ maxInt == 2147483647
+
+  log "maxInt + 1 should equal minInt"
+  assert $ maxInt + 1 == minInt
+
   log "fromNumber should coerce integer values"
   assert $ fromNumber 1.0 == Just 1
   assert $ fromNumber 42.0 == Just 42