diff --git a/Makefile b/Makefile
index 39802f9..6816f5a 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,7 @@ LDFLAGS = -lm -lc
 
 CC = cc
 
-SRC = cirilisp.c read.c print.c
+SRC = cirilisp.c read.c eval.c print.c util.c
 OBJ = $(SRC:.c=.o)
 
 all: cirilisp
@@ -21,7 +21,7 @@ all: cirilisp
 .c.o:
 	$(CC) -c $(CFLAGS) $<
 
-$(OBJ): util.h read.h print.h
+$(OBJ): util.h read.h eval.h print.h
 
 cirilisp: $(OBJ)
 	$(CC) -o $@ $(OBJ) $(LDFLAGS)
@@ -31,7 +31,7 @@ clean:
 
 dist: clean
 	mkdir -p cirilisp-$(VERSION)
-	cp -r Makefile readline.h $(SRC) cirilisp-$(VERSION)
+	cp -r Makefile util.h read.h eval.h print.h $(SRC) cirilisp-$(VERSION)
 	tar -cf cirilisp-$(VERSION).tar cirilisp-$(VERSION)
 	gzip cirilisp-$(VERSION).tar
 	rm -rf cirilisp-$(VERSION)
diff --git a/cirilisp.c b/cirilisp.c
index 535b669..9c444fe 100644
--- a/cirilisp.c
+++ b/cirilisp.c
@@ -4,6 +4,7 @@
 
 #include "util.h"
 #include "read.h"
+#include "eval.h"
 #include "print.h"
 
 int main(int argc, char **argv)
@@ -18,9 +19,7 @@ int main(int argc, char **argv)
 
 	for (;;)
 	{
-		print(read("ШКЉ> "));
-		/* append(&tokenList, lexLine(readline()));
-		printTokenList(tokenList); */
+		print(eval(read("ШКЉ> ")));
 	}
 }
 
diff --git a/eval.c b/eval.c
new file mode 100644
index 0000000..8b886a9
--- /dev/null
+++ b/eval.c
@@ -0,0 +1,233 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "util.h"
+
+char *improperListError = "Конс објекат мора бити правилна листа да би\
+ могао бити евалуиран";
+char *typeError = "Неправилан тип аргумента прослеђен функцији";
+char *unrecognizedSymbolError = "Непознати симбол";
+char *notApplicableError = "Објекат није примењив";
+char *divisionByZeroError = "Дељење нулом";
+char *argumentNumberError = "Функцији није прослеђен правилан број аргумената";
+
+object apply(object function, object parameters);
+
+object eval(object input)
+{
+	object result;
+
+	if (TYPE(input) == nilObject || TYPE(input) == numberObject ||
+			TYPE(input) == errorObject)
+		result = input;
+	else if (TYPE(input) == symbolObject)
+	{
+		if (!strcmp(SYM(input), "+") || !strcmp(SYM(input), "-") ||
+		    !strcmp(SYM(input), "*") || !strcmp(SYM(input), "/"))
+		{
+			result = input;
+		}
+		else
+		{
+			deleteObject(input);
+			TYPE(result) = errorObject;
+			ERRMSG(result) = unrecognizedSymbolError;
+		}
+	}
+	else if (TYPE(input) == consObject)
+	{
+		if (!properList(input))
+		{
+			deleteObject(input);
+			TYPE(result) = errorObject;
+			ERRMSG(result) = improperListError;
+		}
+
+		object *currentCell = &input;
+		int noErrors = 1;
+		while (TYPE(*currentCell) != nilObject)
+		{
+			CAR(*currentCell) = eval(CAR(*currentCell));
+
+			if (TYPE(CAR(*currentCell)) == errorObject)
+			{
+				noErrors = 0;
+				TYPE(result) = errorObject;
+				ERRMSG(result) = ERRMSG(CAR(*currentCell));
+				break;
+			}
+			currentCell = &CDR(*currentCell);
+		}
+
+		if (noErrors)
+		{
+			result = apply(CAR(input), CDR(input));
+		}
+		deleteObject(input);
+	}
+
+	return result;
+}
+
+object add(object parameters);
+object subtract(object parameters);
+object multiply(object parameters);
+object divide(object parameters);
+
+object apply(object function, object parameters)
+{
+	object result;
+
+	if (TYPE(function) != symbolObject)
+	{
+		deleteObject(function);
+		TYPE(result) = errorObject;
+		ERRMSG(result) = notApplicableError;
+	}
+	/* TODO Ово налажење ће се касније извршавати кроз табелу симбола */
+	else if (!strcmp(SYM(function), "+"))
+	{
+		result = add(parameters);
+	}
+	else if (!strcmp(SYM(function), "-"))
+	{
+		result = subtract(parameters);
+	}
+	else if (!strcmp(SYM(function), "*"))
+	{
+		result = multiply(parameters);
+	}
+	else if (!strcmp(SYM(function), "/"))
+	{
+		result = divide(parameters);
+	}
+	else
+	{
+		deleteObject(function);
+		TYPE(result) = errorObject;
+		ERRMSG(result) = improperListError;
+	}
+
+	return result;
+}
+
+int allNumbers(object list)
+{
+	object *currentCell = &list;
+	while (TYPE(*currentCell) != nilObject)
+	{
+		if (TYPE(CAR(*currentCell)) != numberObject)
+		{
+			return 0;
+		}
+		currentCell = &CDR(*currentCell);
+	}
+	return 1;
+}
+
+object add(object parameters)
+{
+	object result;
+	TYPE(result) = numberObject;
+
+	if (!allNumbers(parameters))
+	{
+		TYPE(result) = errorObject;
+		ERRMSG(result) = typeError;
+	}
+	else if (listLength(parameters) == 0)
+	{
+		NUM(result) = 0LL;
+	}
+	else
+	{
+		object first, rest;
+		first = CAR(parameters);
+		rest = add(CDR(parameters));
+
+		NUM(result) = NUM(first) + NUM(rest);
+	}
+
+	return result;
+}
+
+object subtract(object parameters)
+{
+	object result;
+	TYPE(result) = numberObject;
+
+	if (!allNumbers(parameters))
+	{
+		TYPE(result) = errorObject;
+		ERRMSG(result) = typeError;
+	}
+	else if (listLength(parameters) == 0)
+	{
+		TYPE(result) = errorObject;
+		ERRMSG(result) = argumentNumberError;
+	}
+	else if (listLength(parameters) == 1)
+	{
+		NUM(result) = -NUM(CAR(parameters));
+	}
+	else
+	{
+		NUM(result) = NUM(CAR(parameters)) - NUM(add(CDR(parameters)));
+	}
+
+	return result;
+}
+
+object multiply(object parameters)
+{
+	object result;
+	TYPE(result) = numberObject;
+
+	if (!allNumbers(parameters))
+	{
+		TYPE(result) = errorObject;
+		ERRMSG(result) = typeError;
+	}
+	else if (listLength(parameters) == 0)
+	{
+		NUM(result) = 1LL;
+	}
+	else
+	{
+		object first, rest;
+		first = CAR(parameters);
+		rest = multiply(CDR(parameters));
+
+		NUM(result) = NUM(first) * NUM(rest);
+	}
+
+	return result;
+}
+
+object divide(object parameters)
+{
+	object result;
+	TYPE(result) = numberObject;
+
+	if (!allNumbers(parameters))
+	{
+		TYPE(result) = errorObject;
+		ERRMSG(result) = typeError;
+	}
+	else if (listLength(parameters) == 0)
+	{
+		TYPE(result) = errorObject;
+		ERRMSG(result) = argumentNumberError;
+	}
+	else if (listLength(parameters) == 1)
+	{
+		NUM(result) = 1/NUM(CAR(parameters));
+	}
+	else
+	{
+		NUM(result) = NUM(CAR(parameters))/NUM(add(CDR(parameters)));
+	}
+
+	return result;
+}
diff --git a/eval.h b/eval.h
new file mode 100644
index 0000000..13f8a37
--- /dev/null
+++ b/eval.h
@@ -0,0 +1,3 @@
+#pragma once
+
+object eval(object input);
diff --git a/print.c b/print.c
index 1ce44d0..0116963 100644
--- a/print.c
+++ b/print.c
@@ -6,31 +6,38 @@ void printValue(object input);
 
 void print(object input)
 {
-	printf("\n; Value: ");
-	printValue(input);
-	printf("\n\n");
+	if (input.type == errorObject)
+	{
+		fprintf(stderr, "\nГРЕШКА: %s\n\n", ERRMSG(input));
+	}
+	else
+	{
+		printf("\n; Value: ");
+		printValue(input);
+		printf("\n\n");
+	}
 }
 
 void printValue(object input)
 {
 	if (input.type == nilObject)
 	{
-		printf("nil");
+		printf("()");
 	}
 	else if (input.type == numberObject)
 	{
-		printf("%lld", *((long long *) input.address));
+		printf("%lld", NUM(input));
 	}
 	else if (input.type == symbolObject)
 	{
-		printf("%s", (char *) input.address);
+		printf("%s", SYM(input));
 	}
 	else if (input.type == consObject)
 	{
 		printf("(");
-		printValue(((cons *) input.address)->car);
+		printValue(CAR(input));
 		printf(" . ");
-		printValue(((cons *) input.address)->cdr);
+		printValue(CDR(input));
 		printf(")");
 	}
 }
diff --git a/read.c b/read.c
index 392fa08..2d2da66 100644
--- a/read.c
+++ b/read.c
@@ -24,36 +24,36 @@ typedef struct _Token
 	struct _Token *next;
 } token;
 
-int completeSExpr(token **tokenList);
+int completeExpression(token **tokenQueue);
 char *readline();
 void append(token **head, token *appendix);
 token *lexLine(char *input);
-object parseObject(token **inputList);
+object parseExpression(token **inputList);
 
-token *tokenList = NULL;
+token *tokenQueue = NULL;
 
 object read(char *prompt)
 {
 	printf("%s", prompt);
 
-	while (!completeSExpr(&tokenList))
+	while (!completeExpression(&tokenQueue))
 	{
 		char *input = readline();
-		if (input == NULL) /* унесен је EOF сигнал */
+		if (input == NULL) /* унесен је EOF */
 		{
 			printf("\nКрај улазног стрима.\n");
 			exit(0);
 		}
-		append(&tokenList, lexLine(input));
+		append(&tokenQueue, lexLine(input));
 	}
 
-	return parseObject(&tokenList);
+	return parseExpression(&tokenQueue);
 }
 
-int completeSExpr(token **tokenList)
+int completeExpression(token **tokenQueue)
 {
 	int result = 0, indentLevel = 0;
-	token *current = *tokenList;
+	token *current = *tokenQueue;
 
 	while (current != NULL)
 	{
@@ -65,7 +65,7 @@ int completeSExpr(token **tokenList)
 		{
 			if (indentLevel == 0)
 			{
-				token **deleteParen = tokenList;
+				token **deleteParen = tokenQueue;
 				while (*deleteParen != current)
 				{
 					deleteParen = &(*deleteParen)->next;
@@ -115,7 +115,8 @@ char *readline()
 	char *cpy = malloc(strlen(buffer)+1);
 	strcpy(cpy, buffer);
 	cpy[strlen(cpy)-1] = '\0';
-	// Уклања завршни њу-лајн или ЕОФ у стрингу и копира га на ново место
+	/* Уклања завршни њу-лајн или ЕОФ у стрингу
+	 * и копира стринг на ново место */
 
 	return cpy;
 }
@@ -141,7 +142,7 @@ token *lex1Token(char *input, int *i)
 	regcomp(&regSpace, "^[[:space:]]*", REG_EXTENDED);
 
 	regcomp(&regNumber, "^[-+]?[[:digit:]]+", REG_EXTENDED);
-	regcomp(&regSymbol, "^[-+/*]", REG_EXTENDED);
+	regcomp(&regSymbol, "^[-+/*]+", REG_EXTENDED);
 /* за сада подржава само симболе -, +, * и / */
 	regcomp(&regLParenthesis, "^\\(", REG_EXTENDED);
 	regcomp(&regRParenthesis, "^\\)", REG_EXTENDED);
@@ -206,7 +207,7 @@ token *lexLine(char *input)
 		if ((*new)->type == undefinedToken)
 		{
 /* уколико се у реду нађе токен који је лексички погрешан, штампа се место тог
-токена у реду и бришу се сви токени нађени у реду, функција враћа NULL*/
+ * токена у реду и бришу се сви токени нађени у реду, функција враћа NULL*/
 			fprintf(stderr, "Невалидан токен на месту %d\n", i);
 			new = &root;
 			while (*new != NULL)
@@ -223,27 +224,29 @@ token *lexLine(char *input)
 	return root;
 }
 
-object parseObject(token **inputList)
+object parseExpression(token **inputList)
 {
 	object result;
 
 	token input = **inputList;
 	free(*inputList);
 	*inputList = input.next;
+	/* скида први преостали токен са листе унесених, да би се могао
+	 * прерадити */
 
 	if (input.type == numberToken)
 	{
-		result.type = numberObject;
-		result.address = malloc(sizeof(long long int));
-		*((long long *) result.address) = atoll(input.lexeme);
+		TYPE(result) = numberObject;
+		NUM(result) = atoll(input.lexeme);
 		return result;
 	}
 	else if (input.type == symbolToken)
 	{
-		result.type = symbolObject;
-		result.address = malloc((strlen(input.lexeme) + 1)
-					 * sizeof(char));
-		strcpy((char *) result.address, input.lexeme);
+		TYPE(result) = symbolObject;
+		SYM(result) = malloc((strlen(input.lexeme) + 1)
+					* sizeof(char));
+		/* Алокација стринга */
+		strcpy(SYM(result), input.lexeme);
 		return result;
 	}
 	else if (input.type == lParenthesisToken)
@@ -252,17 +255,16 @@ object parseObject(token **inputList)
 
 		while ((*inputList)->type != rParenthesisToken)
 		{
-			listCurrent->type = consObject;
-			listCurrent->address = malloc(sizeof(cons));
+			TYPE(*listCurrent) = consObject;
+			CONS(*listCurrent) = malloc(sizeof(cons));
+			/* Алокација конс ћелије */
 
-			((cons *) listCurrent->address)->car =
-				parseObject(inputList);
+			CAR(*listCurrent) = parseExpression(inputList);
 
-			listCurrent = &(((cons *) listCurrent->address)->cdr);
+			listCurrent = &CDR(*listCurrent);
 		}
 
-		(*listCurrent).type = nilObject;
-		(*listCurrent).address = NULL;
+		TYPE(*listCurrent) = nilObject;
 
 		input = **inputList;
 		free(*inputList);
diff --git a/util.c b/util.c
new file mode 100644
index 0000000..72395f2
--- /dev/null
+++ b/util.c
@@ -0,0 +1,72 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include "util.h"
+
+int properList(object list)
+{
+	object *current = &list;
+	while (TYPE(*current) == consObject)
+	{
+		current = &CDR(*current);
+	}
+	return TYPE(*current) == nilObject;
+}
+
+int listLength(object list)
+{
+	object *current = &list;
+	int i = 0;
+	while (TYPE(*current) != nilObject)
+	{
+		current = &CDR(*current);
+		++i;
+	}
+	return i;
+}
+
+void deleteObject(object input)
+{
+	if ((TYPE(input) == symbolObject) && SYM(input) != NULL)
+	{
+		free(SYM(input));
+		SYM(input) = NULL;
+	}
+	else if (TYPE(input) == consObject)
+	{
+		deleteObject(CAR(input));
+		deleteObject(CDR(input));
+		free(CONS(input));
+		CONS(input) = NULL;
+	}
+
+	TYPE(input) = nilObject;
+}
+
+object copyObject(object input)
+{
+	object result;
+	TYPE(result) = TYPE(input);
+	if (TYPE(input) == errorObject)
+	{
+		ERRMSG(result) = ERRMSG(input);
+	}
+	else if (TYPE(input) == numberObject)
+	{
+		NUM(result) = NUM(input);
+	}
+	else if (TYPE(input) == symbolObject)
+	{
+		SYM(result) =
+			malloc(sizeof(char) * (strlen(SYM(input)) + 1));
+		strcpy(SYM(result), SYM(input));
+	}
+	else if (TYPE(input) == consObject)
+	{
+		CONS(result) = malloc(sizeof(cons));
+		CAR(result) = copyObject(CAR(input));
+		CDR(result) = copyObject(CDR(input));
+	}
+
+	return result;
+}
diff --git a/util.h b/util.h
index cadc0ad..ee2d640 100644
--- a/util.h
+++ b/util.h
@@ -1,22 +1,45 @@
 #pragma once
 
+#define TYPE(x) ((x).type)
+
+#define CONS(x) ((x).value.consCell)
+#define CAR(x) (((x).value.consCell)->car)
+#define CDR(x) (((x).value.consCell)->cdr)
+#define NUM(x) ((x).value.number)
+#define SYM(x) ((x).value.symbol)
+#define ERRMSG(x) ((x).value.errmsg)
+
+typedef struct object object;
+typedef struct cons cons;
+
 typedef enum
 {
 	nilObject,
 	consObject,
 	numberObject,
-	symbolObject
+	symbolObject,
+	errorObject
 } dataType;
 
-typedef struct _Object
+struct object
 {
 	dataType type;
-	void *address;
-} object;
+	union
+	{
+		char *errmsg;
+		char *symbol;
+		long long int number;
+		cons *consCell;
+	} value;
+};
 
-typedef struct _Cons
+struct cons
 {
 	object car;
 	object cdr;
-} cons;
+};
 
+int properList(object list);
+int listLength(object list);
+void deleteObject(object input);
+object copyObject(object input);