Rational.toDecimalString doesn't return the correct sign

Since -1 // 3 = 0 the sign is lost. I needed to capture the sign and display it separately.
dwayne · Jul 11, 2019 · 87c4978 · 87c4978
1 parent 375b155
commit 87c4978
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Showing 2 changed files with 17 additions and 3 deletions.
diff --git a/src/Rational.elm b/src/Rational.elm
@@ -94,13 +94,22 @@ toDecimalString (Rational n d) =
     String.fromInt n
   else
     let
+      sign =
+        if n < 0 then
+          "-"
+        else
+          ""
+
+      m =
+        abs n
+
       quotient =
-        n // d
+        m // d
 
       remainder =
-        modBy d (abs n)
+        modBy d m
     in
-      String.fromInt quotient ++ "." ++ (decimalRep remainder d)
+      sign ++ String.fromInt quotient ++ "." ++ (decimalRep remainder d)
 
 
 decimalRep : Int -> Int -> String

diff --git a/tests/Test/Rational.elm b/tests/Test/Rational.elm
@@ -117,6 +117,11 @@ terminatingDecimalSuite =
           Rational.new 1 2
             |> Maybe.map Rational.toDecimalString
             |> Expect.equal (Just "0.5")
+    , test "-1/2" <|
+        \_ ->
+          Rational.new -1 2
+            |> Maybe.map Rational.toDecimalString
+            |> Expect.equal (Just "-0.5")
     , test "5/2" <|
         \_ ->
           Rational.new 5 2