diff --git a/Makefile b/Makefile
index 7c69a73..ee1607b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,11 @@
+GPP = g++ -Wall
+
 sloth: src/main.c src/parser/lex.yy.o src/parser/parser.tab.o src/variables/environment.o src/variables/variable.o src/variables/value.o src/operations/node.o src/operations/operators.o src/string.o src/shell.o
-	gcc src/main.c src/parser/lex.yy.o src/parser/parser.tab.o src/variables/environment.o src/variables/variable.o src/variables/value.o src/operations/node.o src/operations/operators.o src/string.o src/shell.o -ledit -o sloth
-src/parser/lex.yy.o: src/parser/lex.yy.c src/parser/parser.tab.h
-	gcc -c src/parser/lex.yy.c -o src/parser/lex.yy.o
+	$(GPP) src/main.c src/parser/lex.yy.o src/parser/parser.tab.o src/variables/environment.o src/variables/variable.o src/variables/value.o src/operations/node.o src/operations/operators.o src/string.o src/shell.o -ledit -o sloth
+src/parser/lex.yy.o: src/parser/lex.yy.c src/parser/parser.tab.h 
+	$(GPP) -c src/parser/lex.yy.c -o src/parser/lex.yy.o
 src/parser/parser.tab.o: src/parser/parser.tab.c
-	gcc -c src/parser/parser.tab.c -o src/parser/parser.tab.o
+	$(GPP) -c src/parser/parser.tab.c -o src/parser/parser.tab.o
 src/parser/parser.tab.h: src/parser/parser.y
 	bison -d -o src/parser/parser.tab.c src/parser/parser.y
 src/parser/parser.tab.c: src/parser/parser.y
@@ -11,18 +13,18 @@ src/parser/parser.tab.c: src/parser/parser.y
 src/parser/lex.yy.c: src/parser/lexer.l
 	flex -o src/parser/lex.yy.c src/parser/lexer.l
 src/variables/environment.o: src/variables/environment.h src/variables/environment.c
-	gcc -c src/variables/environment.c -o src/variables/environment.o
+	$(GPP) -c src/variables/environment.c -o src/variables/environment.o
 src/variables/variable.o: src/variables/variable.h src/variables/variable.c
-	gcc -c src/variables/variable.c -o src/variables/variable.o
+	$(GPP) -c src/variables/variable.c -o src/variables/variable.o
 src/variables/value.o: src/variables/value.h src/variables/value.h
-	gcc -c src/variables/value.c -o src/variables/value.o
+	$(GPP) -c src/variables/value.c -o src/variables/value.o
 src/operations/operators.o: src/operations/operators.h  src/operations/operators.c
-	gcc -c src/operations/operators.c -o src/operations/operators.o
+	$(GPP) -c src/operations/operators.c -o src/operations/operators.o
 src/operations/node.o: src/operations/node.h src/operations/node.c
-	gcc -c src/operations/node.c -o src/operations/node.o
+	$(GPP) -c src/operations/node.c -o src/operations/node.o
 src/shell.o: src/shell.h src/shell.c
-	gcc -c src/shell.c -o src/shell.o
+	$(GPP) -c src/shell.c -o src/shell.o
 src/string.o: src/string.h src/string.c
-	gcc -c src/string.c -o src/string.o
+	$(GPP) -c src/string.c -o src/string.o
 clean:
-	rm src/parser/lex.yy.c src/parser/parser.tab.c src/parser/parser.tab.h src/parser/lex.yy.o src/parser/parser.tab.o src/variables/environment.o src/variables/variable.o src/variables/value.o src/operations/node.o src/operations/operators.o src/shell.o sloth
+	rm src/parser/lex.yy.c src/parser/parser.tab.c src/parser/parser.tab.h src/parser/lex.yy.o src/parser/parser.tab.o src/variables/environment.o src/variables/variable.o src/variables/value.o src/operations/node.o src/operations/operators.o src/string.o src/shell.o sloth
diff --git a/src/operations/node.c b/src/operations/node.c
index 191e3e1..a1f5404 100644
--- a/src/operations/node.c
+++ b/src/operations/node.c
@@ -210,19 +210,19 @@ struct Value* eval_expression(struct Node* node, struct Environment* env) {
     //----------
     case AND:
       check_num_nodes(node, 2, "cannot perform logical operators on more than two expressions.");
-      return and(val1, val2);
+      return and_value(val1, val2);
       // return val1 && val2;
       break;
     //----------
     case OR:
       check_num_nodes(node, 2, "cannot perform logical operators on more than two expressions.");
-      return or(val1, val2);
+      return or_value(val1, val2);
       // return val1 || val2;
       break;
     //----------
     case NOT:
       check_num_nodes(node, 1, "cannot negate more than one expressions.");
-      return not(val1);
+      return not_value(val1);
       // return !val1;
       break;
     //----------
diff --git a/src/operations/operators.c b/src/operations/operators.c
index f07ac7c..99d70db 100644
--- a/src/operations/operators.c
+++ b/src/operations/operators.c
@@ -248,7 +248,7 @@ struct Value* not_equals(struct Value* x, struct Value* y) {
   return ans;
 }
 
-struct Value* and(struct Value* x, struct Value* y) {
+struct Value* and_value(struct Value* x, struct Value* y) {
   if (!x || !y) { fprintf(stderr, "Error, uninitialized values being used in &&.\n"); }
   if (x->type != BOOLEAN || y->type != BOOLEAN) { fprintf(stderr, "Error, cannot use and AND operation with a non-boolean.\n"); }
   if (x->type == STRING || y->type == STRING) { fprintf(stderr, "Error, cannot AND a string.\n"); }
@@ -256,7 +256,7 @@ struct Value* and(struct Value* x, struct Value* y) {
   return make_boolean(get_long(x) && get_long(y));
 }
 
-struct Value* or(struct Value* x, struct Value* y) {
+struct Value* or_value(struct Value* x, struct Value* y) {
   if (!x || !y) { fprintf(stderr, "Error, uninitialized values being used in ||.\n"); }
   if (x->type != BOOLEAN || y->type != BOOLEAN) { fprintf(stderr, "Error, cannot use and OR operation with a non-boolean.\n"); }
   if (x->type == STRING || y->type == STRING) { fprintf(stderr, "Error, cannot OR a string.\n"); }
@@ -264,7 +264,7 @@ struct Value* or(struct Value* x, struct Value* y) {
   return make_boolean(get_long(x) || get_long(y));
 }
 
-struct Value* not(struct Value* x) {
+struct Value* not_value(struct Value* x) {
   if (!x) { fprintf(stderr, "Error, uninitialized values being used in !.\n"); }
   if (x->type != BOOLEAN) { fprintf(stderr, "Error, cannot NOT a non-boolean.\n"); }
   if (x->type == STRING) { fprintf(stderr, "Error, cannot negate a string.\n"); }
diff --git a/src/operations/operators.h b/src/operations/operators.h
index 174cea0..9bb8c5b 100644
--- a/src/operations/operators.h
+++ b/src/operations/operators.h
@@ -1,5 +1,6 @@
 #ifndef OPERATORS_H
 #define OPERATORS_H
+#include "../variables/value.h"
 
 struct Value* add(struct Value* x, struct Value* y);
 struct Value* subtract(struct Value* x, struct Value* y);
@@ -11,8 +12,8 @@ struct Value* less_equal(struct Value* x, struct Value* y);
 struct Value* greater_equal(struct Value* x, struct Value* y);
 struct Value* equals(struct Value* x, struct Value* y);
 struct Value* not_equals(struct Value* x, struct Value* y);
-struct Value* and(struct Value* x, struct Value* y);
-struct Value* or(struct Value* x, struct Value* y);
-struct Value* not(struct Value* x);
+struct Value* and_value(struct Value* x, struct Value* y);
+struct Value* or_value(struct Value* x, struct Value* y);
+struct Value* not_value(struct Value* x);
 
 #endif
diff --git a/src/parser/parser.h b/src/parser/parser.h
index aaa1b53..3d1dc96 100644
--- a/src/parser/parser.h
+++ b/src/parser/parser.h
@@ -4,5 +4,6 @@
 int yywrap( );
 int yylex( );
 void yyerror(const char* str);
+int yyparse (void);
 
 #endif
diff --git a/src/shell.c b/src/shell.c
index 775c7d8..1cac0bf 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -1,8 +1,10 @@
 #include <stdio.h>
 #include <string.h>
 #include "shell.h"
+#include "parser/parser.h"
 #include "variables/environment.h"
 #include "operations/node.h"
+#include "constants.h"
 
 
 // For keeping track of command history
@@ -24,9 +26,6 @@ void add_history(char* unused) {}
 #include <editline/readline.h>
 #endif
 
-
-struct Node* result;
-
 FILE* stringToFile(char* str) { // Creates a temporary file with the given string as its contents
     int i = 0; 
   
diff --git a/src/string.c b/src/string.c
index 5f55218..4118f12 100644
--- a/src/string.c
+++ b/src/string.c
@@ -11,7 +11,7 @@ char* substring(char* str, int start, int end) {
   char* substr;
   int c;
   int length = end - start;
-  substr = malloc(length + 1);
+  substr = (char*) malloc(length + 1);
  
   if (substr == NULL) {
     fprintf(stderr, "Unable to allocate memory for substring.\n");
diff --git a/src/variables/value.c b/src/variables/value.c
index b63c44e..ee4892b 100644
--- a/src/variables/value.c
+++ b/src/variables/value.c
@@ -4,7 +4,7 @@
 #include "../parser/parser.tab.h"
 
 
-struct Value* make_value(int type, long num, double dec, struct Node* expr, char* str) {
+struct Value* make_value(TypeTag type, long num, double dec, struct Node* expr, char* str) {
     /* allocate space */
   struct Value* val = (struct Value*) malloc(sizeof(struct Value));