Show Instance for CodePoints

bower.json

@@ -22,7 +22,8 @@
     "purescript-maybe": "^3.0.0",
     "purescript-partial": "^1.2.0",
     "purescript-unfoldable": "^3.0.0",
-    "purescript-arrays": "^4.0.1"
+    "purescript-arrays": "^4.0.1",
+    "purescript-integers": "^3.2.0"
   },
   "devDependencies": {
     "purescript-assert": "^3.0.0",

src/Data/String/CodePoints.purs

@@ -29,6 +29,7 @@ import Prelude
 
 import Data.Array as Array
 import Data.Char as Char
+import Data.Int (hexadecimal, toStringAs)
 import Data.Maybe (Maybe(Just, Nothing))
 import Data.String as String
 import Data.String.Unsafe as Unsafe
@@ -50,6 +51,9 @@ newtype CodePoint = CodePoint Int
 derive instance eqCodePoint :: Eq CodePoint
 derive instance ordCodePoint :: Ord CodePoint
 
+instance showCodePoint :: Show CodePoint where
+  show (CodePoint i) = "(CodePoint 0x" <> String.toUpper (toStringAs hexadecimal i) <> ")"
+
 -- I would prefer that this smart constructor not need to exist and instead
 -- CodePoint just implements Enum, but the Enum module already depends on this
 -- one. To avoid the circular dependency, we just expose these two functions.

test/Test/Data/String/CodePoints.purs

@@ -15,6 +15,15 @@ str = "a\xDC00\xD800\xD800\x16805\x16A06\&z"
 
 testStringCodePoints :: forall eff. Eff (console :: CONSOLE, assert :: ASSERT | eff) Unit
 testStringCodePoints = do
+  log "show"
+  assert $ map show (codePointAt 0 str) == Just "(CodePoint 0x61)"
+  assert $ map show (codePointAt 1 str) == Just "(CodePoint 0xDC00)"
+  assert $ map show (codePointAt 2 str) == Just "(CodePoint 0xD800)"
+  assert $ map show (codePointAt 3 str) == Just "(CodePoint 0xD800)"
+  assert $ map show (codePointAt 4 str) == Just "(CodePoint 0x16805)"
+  assert $ map show (codePointAt 5 str) == Just "(CodePoint 0x16A06)"
+  assert $ map show (codePointAt 6 str) == Just "(CodePoint 0x7A)"
+
   log "codePointAt"
   assert $ codePointAt (-1) str == Nothing
   assert $ codePointAt 0 str == (codePointFromInt 0x61)