(Java) fixing Dockerfile typo

java/Dockerfile

@@ -12,4 +12,4 @@ FROM eclipse-temurin:${JAVA_VERSION}-alpine
 WORKDIR /jmonkey
 COPY --from=build /jmonkey/monkey.jar .
 ENTRYPOINT ["java", "-jar", "monkey.jar"]
-CMD ["let fac = fn (n) { let it = fn (n, acc) { if (n < 1) { acc } else { it(n-1, n*acc) }}; it(n, 1) }; fac(pow(10))"]
+CMD ["let fac = fn (n) { let it = fn (n, acc) { if (n < 1) { acc } else { it(n-1, n*acc) }}; it(n, 1) }; puts(fac(10))"]

java/monkey/src/main/java/root/evaluation/BuiltinFunctions.java

@@ -43,21 +43,19 @@ public enum BuiltinFunctions {
     }),
     UPPERCASE("uppercase", (callToken, arguments) -> {
         AbstractMonkeyFunction.checkArgumentCount(callToken, 1, arguments.size());
-        AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), ObjectType.STRING, "uppercase");
+        var string = AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), MonkeyString.class, "uppercase");
 
-        return new MonkeyString(((MonkeyString) arguments.get(0)).getValue().toUpperCase());
+        return new MonkeyString(string.getValue().toUpperCase());
     }),
     LOWERCASE("lowercase", (callToken, arguments) -> {
         AbstractMonkeyFunction.checkArgumentCount(callToken, 1, arguments.size());
-        AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), ObjectType.STRING, "lowercase");
+        var string = AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), MonkeyString.class, "lowercase");
 
-        return new MonkeyString(((MonkeyString) arguments.get(0)).getValue().toLowerCase());
+        return new MonkeyString(string.getValue().toLowerCase());
     }),
     FIRST("first", (callToken, arguments) -> {
         AbstractMonkeyFunction.checkArgumentCount(callToken, 1, arguments.size());
-        AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), ObjectType.ARRAY, "first");
-
-        var array = (MonkeyArray) arguments.get(0);
+        var array = AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), MonkeyArray.class, "first");
 
         if (array.getValue().isEmpty()) {
             return MonkeyNull.INSTANCE;
@@ -66,9 +64,7 @@ public enum BuiltinFunctions {
     }),
     LAST("last", (callToken, arguments) -> {
         AbstractMonkeyFunction.checkArgumentCount(callToken, 1, arguments.size());
-        AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), ObjectType.ARRAY, "last");
-
-        var array = (MonkeyArray) arguments.get(0);
+        var array = AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), MonkeyArray.class, "last");
 
         if (array.getValue().isEmpty()) {
             return MonkeyNull.INSTANCE;
@@ -77,9 +73,7 @@ public enum BuiltinFunctions {
     }),
     REST("rest", (callToken, arguments) -> {
         AbstractMonkeyFunction.checkArgumentCount(callToken, 1, arguments.size());
-        AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), ObjectType.ARRAY, "rest");
-
-        var array = (MonkeyArray) arguments.get(0);
+        var array = AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), MonkeyArray.class, "rest");
 
         if (array.getValue().isEmpty()) {
             return MonkeyNull.INSTANCE;
@@ -95,9 +89,7 @@ public enum BuiltinFunctions {
     }),
     PUSH("push", (callToken, arguments) -> {
         AbstractMonkeyFunction.checkArgumentCount(callToken, 2, arguments.size());
-        AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), ObjectType.ARRAY, "rest");
-
-        var array = (MonkeyArray) arguments.get(0);
+        var array = AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), MonkeyArray.class, "push");
 
         var elementsCopy = new ArrayList<>(array.getValue());
         elementsCopy.add(arguments.get(1));
@@ -106,13 +98,11 @@ public enum BuiltinFunctions {
     }),
     CHARS("chars", (callToken, arguments) -> {
         AbstractMonkeyFunction.checkArgumentCount(callToken, 1, arguments.size());
-        AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), ObjectType.STRING, "chars");
+        var string = AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), MonkeyString.class, "chars");
 
-        var string = (MonkeyString) arguments.get(0);
-        char[] chars = string.getValue().toCharArray();
         var monkeyChars = new ArrayList<MonkeyObject<?>>();
 
-        for (char c : chars) {
+        for (char c : string.getValue().toCharArray()) {
             monkeyChars.add(new MonkeyString(String.valueOf(c)));
         }
 
@@ -183,9 +173,8 @@ public enum BuiltinFunctions {
     }),
     AS_LIST("asList", (callToken, arguments) -> {
         AbstractMonkeyFunction.checkArgumentCount(callToken, 1, arguments.size());
-        AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), ObjectType.HASH, "asList");
+        var hash = AbstractMonkeyFunction.checkArgumentType(callToken, arguments.get(0), MonkeyHash.class, "asList");
 
-        var hash = (MonkeyHash) arguments.get(0);
         List<MonkeyObject<?>> asList = hash
                 .getValue()
                 .entrySet()

java/monkey/src/main/java/root/evaluation/Evaluator.java

@@ -11,7 +11,9 @@
 import root.evaluation.objects.MonkeyObject;
 import root.evaluation.objects.impl.*;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
 
 public class Evaluator {
 
@@ -308,15 +310,10 @@ private MonkeyObject<?> evalIfExpression(IfExpression ifExpression) throws Evalu
     }
 
     private MonkeyObject<?> evalIdentifierExpression(IdentifierExpression identifier) throws EvaluationException {
-        Optional<MonkeyObject<?>> value = environment.get(identifier.getValue());
-
-        if (value.isEmpty()) {
-            return BuiltinFunctions.getFunction(identifier.getValue()).orElseThrow(() ->
-                    new EvaluationException(identifier.getToken(), "Variable %s is not declared", identifier.getValue())
-            );
-        }
-
-        return value.get();
+        return environment
+                .get(identifier.getValue())
+                .or(() -> BuiltinFunctions.getFunction(identifier.getValue()))
+                .orElseThrow(() -> new EvaluationException(identifier.getToken(), "Variable %s is not declared", identifier.getValue()));
     }
 
     private MonkeyObject<?> evalLetStatement(LetStatement letStatement) throws EvaluationException {

java/monkey/src/main/java/root/evaluation/objects/AbstractMonkeyFunction.java

@@ -15,14 +15,19 @@ public static void checkArgumentCount(LocalizedToken callToken, int expected, in
         }
     }
 
-    public static void checkArgumentType(
+    @SuppressWarnings("unchecked") // It is checked
+    public static <T extends MonkeyObject<?>> T checkArgumentType(
             LocalizedToken callToken,
             MonkeyObject<?> argument,
-            ObjectType expected,
+            Class<T> expected,
             String functionName
     ) throws EvaluationException {
-        if (argument.getType() != expected) {
-            throw new EvaluationException(callToken, "Argument to `%s` must be %s, got %s", functionName, expected, argument.getType());
+        if (expected.isAssignableFrom(argument.getClass())) {
+            return (T) argument;
         }
+
+        ObjectType expectedType = ObjectType.getTypeFromClass(expected);
+
+        throw new EvaluationException(callToken, "Argument to `%s` must be %s, got %s", functionName, expectedType, argument.getType());
     }
 }

java/monkey/src/main/java/root/evaluation/objects/ObjectType.java

@@ -1,14 +1,31 @@
 package root.evaluation.objects;
 
+import root.evaluation.objects.impl.*;
+
+import java.util.Arrays;
+
 public enum ObjectType {
 
-    NULL,
-    BOOLEAN,
-    INTEGER,
-    RETURN_VALUE_OBJ,
-    FUNCTION,
-    BUILTIN_OBJ,
-    STRING,
-    ARRAY,
-    HASH,
+    NULL(MonkeyNull.class),
+    BOOLEAN(MonkeyBoolean.class),
+    INTEGER(MonkeyInteger.class),
+    RETURN_VALUE_OBJ(MonkeyReturn.class),
+    FUNCTION(MonkeyFunction.class),
+    BUILTIN_OBJ(BuiltinFunction.class),
+    STRING(MonkeyString.class),
+    ARRAY(MonkeyArray.class),
+    HASH(MonkeyHash.class);
+
+    private final Class<?> monkeyClass;
+
+    ObjectType(Class<?> monkeyClass) {
+        this.monkeyClass = monkeyClass;
+    }
+
+    public static ObjectType getTypeFromClass(Class<?> tClass) {
+        return Arrays.stream(values())
+                .filter(it -> it.monkeyClass == tClass)
+                .findFirst()
+                .orElseThrow(() -> new IllegalStateException("INTERPRETER BUG: No ObjectType associated with class " + tClass));
+    }
 }

java/monkey/src/test/java/EvaluatorTest.java

@@ -312,6 +312,13 @@ void testErrorHandling() {
                                 Error evaluating the program: Index to an hash must be an Expression that yields an Int, String or Boolean
                                 01: { fn(x) { x }: 'func' }
                                 ------^--------------------"""
+                ),
+                List.of(
+                        "push (10, 10)",
+                        """
+                                Error evaluating the program: Argument to `push` must be ARRAY, got INTEGER
+                                01: push (10, 10)
+                                ---------^-------"""
                 )
         );