replace readFloat exercise with rem exercise (#266)

Author: milesfrain

exercises/chapter2/test/Main.purs

@@ -29,11 +29,13 @@ Note to reader: Delete this line to expand comment block -}
         Assert.equal 3.141592653589793 (circleArea 1.0)
       test "radius 3" do
         Assert.equal 28.274333882308138 (circleArea 3.0)
-    suite "addE" do
-      test "1.23" do
-        Assert.equal 3.948281828459045 (addE "1.23")
-      test "4.56" do
-        Assert.equal 7.278281828459045 (addE "4.56")
+    suite "leftoverCents" do
+      test "23" do
+        Assert.equal 23 (leftoverCents 23)
+      test "456" do
+        Assert.equal 56 (leftoverCents 456)
+      test "-789" do
+        Assert.equal (-89) (leftoverCents (-789))
 
 {- Note to reader: Delete this line to expand comment block
 -}

exercises/chapter2/test/no-peeking/Solutions.purs

@@ -1,11 +1,11 @@
 module Test.NoPeeking.Solutions where
 
 import Prelude
-import Global (readFloat)
+import Data.Int (rem)
 import Math (e, pi, sqrt)
 
 diagonal w h = sqrt (w * w + h * h)
 
 circleArea r = pi * r * r
 
-addE s = readFloat s + e
+leftoverCents n = rem n 100

text/chapter2.md

@@ -109,7 +109,7 @@ Success! Now you're ready to try these next exercises on your own.
 ## Exercises
 
  1. (Easy) Write a function `circleArea` which computes the area of a circle with a given radius. Use the `pi` constant, which is defined in the `Math` module. _Hint_: don't forget to import `pi` by modifying the `import Math` statement.
- 1. (Medium) The `readFloat` function converts a String to a floating-point Number. Calling `readFloat "1.23"` produces `1.23`. Write a function `addE` which takes a `String`, converts it to a `Number` with `readFloat`, and then adds the mathematical constant `e` to it. _Hint_: You should first search [Pursuit](https://pursuit.purescript.org/) to find the module that contains the `readFloat` function and import that module.
+ 1. (Medium) Write a function `leftoverCents` which takes an `Integer` and returns what's leftover after dividing by `100`. Use the `rem` function. Search [Pursuit](https://pursuit.purescript.org/) for this function to learn about usage and which module to import it from. _Note:_ Your IDE may support auto-importing of this function if you accept the auto-completion suggestion.
 
 ## Conclusion