Add support for not equals (!=) infix operation.

src/main/kotlin/gay/pizza/pork/ast/nodes/InfixOperator.kt

@@ -5,5 +5,6 @@ enum class InfixOperator(val token: String) {
   Minus("-"),
   Multiply("*"),
   Divide("/"),
-  Equals("==")
+  Equals("=="),
+  NotEquals("!=")
 }

src/main/kotlin/gay/pizza/pork/eval/PorkEvaluator.kt

@@ -81,6 +81,9 @@ class PorkEvaluator(root: Scope) : NodeVisitor<Any> {
       InfixOperator.Equals -> {
         return left == right
       }
+      InfixOperator.NotEquals -> {
+        return left != right
+      }
       else -> {}
     }
 

src/main/kotlin/gay/pizza/pork/parse/PorkParser.kt

@@ -117,7 +117,8 @@ class PorkParser(source: PeekableSource<Token>) {
         TokenType.Minus,
         TokenType.Multiply,
         TokenType.Divide,
-        TokenType.Equality)) {
+        TokenType.Equality,
+        TokenType.Inequality)) {
       val infixToken = next()
       val infixOperator = convertInfixOperator(infixToken)
       return InfixOperation(expression, infixOperator, readExpression())
@@ -133,6 +134,7 @@ class PorkParser(source: PeekableSource<Token>) {
       TokenType.Multiply -> InfixOperator.Multiply
       TokenType.Divide -> InfixOperator.Divide
       TokenType.Equality -> InfixOperator.Equals
+      TokenType.Inequality -> InfixOperator.NotEquals
       else -> throw RuntimeException("Unknown Infix Operator")
     }
 

src/main/kotlin/gay/pizza/pork/parse/TokenType.kt

@@ -6,6 +6,7 @@ enum class TokenType(vararg properties: TokenTypeProperty) {
   Symbol,
   IntLiteral,
   Equality,
+  Inequality,
   Equals(SingleChar('='), Promotion('=', Equality)),
   Plus(SingleChar('+')),
   Minus(SingleChar('-')),
@@ -17,7 +18,7 @@ enum class TokenType(vararg properties: TokenTypeProperty) {
   RightBracket(SingleChar(']')),
   LeftParentheses(SingleChar('(')),
   RightParentheses(SingleChar(')')),
-  Negation(SingleChar('!')),
+  Negation(SingleChar('!'), Promotion('=', Inequality)),
   Comma(SingleChar(',')),
   False(Keyword("false")),
   True(Keyword("true")),