Handle dotted Case clause

src/main/kotlin/function/builtin/special/Case.kt

@@ -8,7 +8,7 @@ import function.builtin.predicate.EQUAL.isEqual
 import sexpression.Cons
 import sexpression.Nil
 import sexpression.SExpression
-import sexpression.Symbol
+import sexpression.Symbol.Companion.T
 
 @FunctionNames("CASE")
 class Case(name: String) : LispSpecialFunction() {
@@ -35,38 +35,27 @@ class Case(name: String) : LispSpecialFunction() {
         val keyList = clause.first
 
         return if (isMatch(key, keyList))
-            evaluateConsequents(clause.rest)
+            evaluateConsequents(clause)
         else
             callTailRecursive(key, remainingClauses)
     }
 
     private fun isMatch(key: SExpression, keyList: SExpression) = when {
         keyList.isNull -> false
-        keyList.isCons -> containsMatch(key, keyList)
-        else           -> isEqual(key, keyList) || isEqual(Symbol.T, keyList)
+        keyList.isCons -> containsMatch(key, keyList as Cons)
+        else           -> isEqual(key, keyList) || isEqual(T, keyList)
     }
 
-    private fun containsMatch(key: SExpression, keyList: SExpression): Boolean {
-        if (keyList.isCons) {
-            (keyList as Cons).forEach {
+    private fun containsMatch(key: SExpression, keyList: Cons): Boolean {
+        keyList.forEach {
             if (isEqual(key, it.first)) {
                 return true
             }
         }
-        }
 
         return false
     }
 
-    private fun evaluateConsequents(consequentList: SExpression): SExpression {
-        var lastConsequentValue: SExpression = Nil
-
-        if (consequentList.isCons) {
-            (consequentList as Cons).forEach {
-                lastConsequentValue = eval(it.first)
-            }
-        }
-
-        return lastConsequentValue
-    }
+    private fun evaluateConsequents(clause: Cons) =
+        clause.drop(1).fold(Nil as SExpression) { _, it -> eval(it.first) }
 }

src/test/kotlin/function/builtin/special/CaseTest.kt

@@ -203,4 +203,11 @@ class CaseTest : SymbolAndFunctionCleaner() {
             evaluateString("(case :a nil)")
         }
     }
+
+    @Test
+    fun caseWithDottedClause() {
+        val input = "(eval `(case :a ,(cons :a 'banana)))"
+
+        assertSExpressionsMatch(parseString("nil"), evaluateString(input))
+    }
 }