diff --git a/proj3/.gitignore b/proj3/.gitignore
new file mode 100644
index 0000000..183ab06
--- /dev/null
+++ b/proj3/.gitignore
@@ -0,0 +1,10 @@
+.vscode
+.DS_Store
+.bloop
+.metals
+**/target
+**/.bloop
+**/.metals
+gen/*
+!gen/bootstrap.c
+metals.*
\ No newline at end of file
diff --git a/proj3/src/main/scala/project3/Compiler.scala b/proj3/src/main/scala/project3/Compiler.scala
index 4ae709b..d497e13 100644
--- a/proj3/src/main/scala/project3/Compiler.scala
+++ b/proj3/src/main/scala/project3/Compiler.scala
@@ -52,7 +52,9 @@ abstract class X86Compiler extends BugReporter with Codegen {
    */
   val primitives = Map(
     "putchar" -> Func("putchar"),
-    "getchar" -> Func("getchar"))
+    "getchar" -> Func("getchar"),
+    "toInt" -> Func("toInt"),
+    "toChar" -> Func("toChar"))
 
   private class Env {
     def undef(name: String) = BUG(s"Undefined identifier $name (should have been found during the semantic analysis)")
@@ -124,6 +126,28 @@ abstract class X86Compiler extends BugReporter with Codegen {
       emitln(s"cmp ${loc(sp1)}, ${loc(sp)}")
       emitln(s"sete %al")
       emitln(s"movzbq %al, ${loc(sp)}")
+    case "!=" =>
+      emitln(s"cmp ${loc(sp1)}, ${loc(sp)}")
+      emitln(s"setne %al")
+      emitln(s"movzbq %al, ${loc(sp)}")
+    case ">=" =>
+      emitln(s"cmp ${loc(sp1)}, ${loc(sp)}")
+      emitln(s"setge %al")
+      emitln(s"movzbq %al, ${loc(sp)}")
+    case ">" =>
+      emitln(s"cmp ${loc(sp1)}, ${loc(sp)}")
+      emitln(s"setg %al")
+      emitln(s"movzbq %al, ${loc(sp)}")      
+    case "<=" =>
+      emitln(s"cmp ${loc(sp1)}, ${loc(sp)}")
+      emitln(s"setle %al")
+      emitln(s"movzbq %al, ${loc(sp)}")
+    case "<" =>
+      emitln(s"cmp ${loc(sp1)}, ${loc(sp)}")
+      emitln(s"setl %al")
+      emitln(s"movzbq %al, ${loc(sp)}")
+    case "block-get" => 
+      emitln(s"movq (${loc(sp)}, ${loc(sp1)}, 8), ${loc(sp)}")
     case _ => BUG(s"Binary operator $op undefined")
   }
 
@@ -136,6 +160,9 @@ abstract class X86Compiler extends BugReporter with Codegen {
    * Valid operators: block-set
    */
   def transTer(op: String)(sp: Loc, sp1: Loc, sp2: Loc) = op match {
+    case "block-set" => 
+      emitln(s"movq ${loc(sp2)}, (${loc(sp)}, ${loc(sp1)}, 8)")
+      emitln(s"movq ${loc(sp2)}, ${loc(sp)}") // returns rhs
     case _ => BUG(s"ternary operator $op undefined")
   }
 
@@ -173,7 +200,9 @@ abstract class X86Compiler extends BugReporter with Codegen {
    * if the location 'sp' contains the value 'true'
    */
   def transJumpIfTrue(sp: Loc)(label: Label) = {
-    ???
+    emitln(s"movq $$1, ${loc(sp + 1)}")
+    emitln(s"cmp ${loc(sp)}, ${loc(sp + 1)}")
+    emitln(s"je $label")
   }
 
   /*
@@ -188,7 +217,13 @@ abstract class X86Compiler extends BugReporter with Codegen {
   def trans(exp: Exp, sp: Loc)(env: LocationEnv): Unit = exp match {
     case Lit(x: Int) =>
       emitln(s"movq $$$x, ${loc(sp)}")
-    case Lit(b: Boolean) => () // TODO
+    case Lit(x: Char) =>
+      emitln(s"movq $$${x.toInt}, ${loc(sp)}")
+    case Lit(b: Boolean) =>  // TODO
+      if(b) 
+        emitln(s"movq $$1, ${loc(sp)}")
+      else 
+        emitln(s"movq $$0, ${loc(sp)}")
     case Lit(x: Unit) => () // TODO
     case Prim(op, args) =>
       val idxs = List.tabulate(args.length)(i => sp + i)
@@ -205,7 +240,7 @@ abstract class X86Compiler extends BugReporter with Codegen {
     case Ref(x) =>
       env(x) match {
         case Reg(sp1) => emitln(s"movq ${loc(sp1)}, ${loc(sp)}")
-        case Func(name) => ??? // Extra credit
+        case Func(name) => emitln(s"leaq ${funcName(name)}(%rip), ${loc(sp)}") // Extra credit
       }
     case If(cond, tBranch, eBranch) =>
       val lab = freshLabel("if")
@@ -233,12 +268,24 @@ abstract class X86Compiler extends BugReporter with Codegen {
       transJumpIfTrue(sp)(s"${lab}_body")
       trans(body, sp)(env)
     case LetRec(funs, body) =>
+      emitln(s"${funcName("toInt")}:", 0)
+      emitln(s"movzbq %dil, %rax")
+      emitln(s"ret\n")
+
+      emitln(s"${funcName("toChar")}:", 0)
+      emitln(s"movzbq %dil, %rax")
+      emitln("ret\n")
+
       emitln("################# FUNCTIONS #####################", 0)
       // We do not save the location of the function into register because we can use their
       // name as a label.
       val funsLoc = funs map { case FunDef(name, _, _, _) => (name, Func(name)) }
 
       // TODO complete the code
+      funs map { 
+        case func@FunDef(_, _, _, _) => 
+          trans(func, Reg(0))(env.withVals(funsLoc))
+      }
 
       emitln("#################################################\n\n", 0)
       emitln("###################### MAIN #####################", 0)
@@ -257,7 +304,8 @@ abstract class X86Compiler extends BugReporter with Codegen {
 
       // emit the main function (body of LetRec) here
       // TODO you may need to change that code.
-      trans(body, Reg(0))(LocationEnv())
+      trans(body, Reg(0))(LocationEnv().withVals(funsLoc))
+
       emitln(s"movq ${loc(0)}, %rax")
 
       //////////// DO NOT CHANGE////////////////
@@ -280,6 +328,10 @@ abstract class X86Compiler extends BugReporter with Codegen {
       //////////////////////////////////////////
 
       // TODO
+      val ids = (0 until args.length).toList
+      val arg_regs = (args zip ids) map {case (Arg(fname, _, _), idx) => (fname, sp + idx)}
+      trans(fbody, sp + args.length)(env.withVals(arg_regs))
+      emitln(s"movq ${loc(sp + args.length)}, %rax")
 
       //////////// DO NOT CHANGE////////////////
       emitln("movq %rbp, %rsp\t# reset frame")
@@ -292,27 +344,51 @@ abstract class X86Compiler extends BugReporter with Codegen {
       // code and work on multiple arguments.
       // Evaluate the arguments
       // TODO
-
+      val ids = (0 until args.length).toList
+      (args zip ids) map {case (arg, idx) => trans(arg, sp + idx)(env)}
       // Compute the physical location of the function to be called
       val fLoc: String = fun match {
         case Ref(fname) =>
           env(fname) match {
-            case Reg(sp) => ??? // Extra credit
-            case Func(name) => "" // TODO
+            case Reg(sp) => s"*${loc(sp)}" // Extra credit
+            case Func(name) => funcName(name) // TODO
           }
-        case _ => ??? // Extra credit
+        case _ => // return from another invocation
+          trans(fun, sp)(env);
+          s"*${loc(sp)}"
       }
 
       // Implement the calling conventions after that point
       // and generate the function call
       // TODO
-      ()
+      val spID : Int = sp match {
+        case Reg(i) => i
+      }
+
+      for(i <- 0 to spID){
+        emitln(s"pushq ${loc(i)}");
+      }
+
+      for(i <- 0 to spID) {
+        emitln(s"movq ${loc(sp + i)}, ${loc(i)}")
+      }
+      emitln(s"call ${fLoc}")
+
+      for(i <- spID to 0 by -1) {
+        emitln(s"popq ${loc(i)}");
+      }
+      emitln(s"movq %rax, ${loc(sp)}")
+
     case ArrayDec(size, _) =>
       // This node needs to allocate an area of eval(size) * 8 bytes in the heap
       // the assembly variable "heap" contains a pointer to the first valid byte
       // in the heap. Make sure to update its value accordingly.
       // TODO
-      ()
+      emitln(s"movq (%rip), ${loc(sp)}")
+      trans(size, sp + 1)(env)
+      emitln(s"movq (%rip), ${loc(sp + 2)}")
+      emitln(s"movq (${loc(sp + 2)}, ${loc(sp + 1)}, 8), ${loc(sp + 2)}")
+      emitln(s"movq ${loc(sp + 2)}, %rip")
     case _ => BUG(s"don't know how to implement $exp")
   }
 }
diff --git a/proj3/src/main/scala/project3/Interpreter.scala b/proj3/src/main/scala/project3/Interpreter.scala
index 62a948a..9fad5fe 100644
--- a/proj3/src/main/scala/project3/Interpreter.scala
+++ b/proj3/src/main/scala/project3/Interpreter.scala
@@ -19,7 +19,9 @@ class ValueInterpreter extends Interpreter with BugReporter {
    */
   val primitives = Map[String, BoxedVal](
     "putchar" -> BoxedVal(Primitive("putchar")),
-    "getchar" -> BoxedVal(Primitive("getchar"))
+    "getchar" -> BoxedVal(Primitive("getchar")),
+    "toInt" -> BoxedVal(Primitive("toInt")),
+    "toChar" -> BoxedVal(Primitive("toChar"))
   )
 
   /*
@@ -204,6 +206,12 @@ class ValueInterpreter extends Interpreter with BugReporter {
           Console.out.write(c)
           Console.out.flush
           Cst(())
+        case Primitive("toInt") => 
+          val List(Cst(c: Char)) = eargs
+          Cst(c.toInt)
+        case Primitive("toChar") => 
+          val List(Cst(c: Int)) = eargs
+          Cst(c.toChar)
       }
     case ArrayDec(size, _) =>
       val Cst(s: Int) = eval(size)(env)
@@ -225,7 +233,9 @@ object StackVal extends BugReporter {
    */
   val primitives = Map[String, Loc](
     "putchar" -> 0,
-    "getchar" -> 1
+    "getchar" -> 1,
+    "toInt" -> 2,
+    "toChar" -> 3
   )
 
   /**
@@ -303,6 +313,8 @@ class StackInterpreter extends Interpreter with BugReporter {
   val memory = new Array[Val](1000)
   memory(0) = Primitive("putchar")
   memory(1) = Primitive("getchar")
+  memory(2) = Primitive("toInt")
+  memory(3) = Primitive("toChar")
   var flag: Boolean = true
 
   /*
@@ -332,12 +344,15 @@ class StackInterpreter extends Interpreter with BugReporter {
     case (">=", Cst(x: Int), Cst(y: Int)) => memory(sp) = Cst(x >= y)
     case ("<" , Cst(x: Int), Cst(y: Int)) => memory(sp) = Cst(x <  y)
     case (">" , Cst(x: Int), Cst(y: Int)) => memory(sp) = Cst(x >  y)
-    case ("block-get", Cst(arr: Array[Any]), Cst(i: Int)) => ???
+    case ("block-get", Cst(arr: Array[Any]), Cst(i: Int)) => 
+      if (arr(i) == null)
+        BUG(s"uninitialized memory")
+      memory(sp) = Cst(arr(i))
     case _    => BUG(s"Binary operator $op undefined")
   }
 
   def evalTer(op: String)(sp: Loc, sp1: Loc, sp2: Loc) = (op, memory(sp), memory(sp1), memory(sp2)) match {
-    case ("block-set", Cst(arr: Array[Any]), Cst(i: Int), Cst(x)) => ???
+    case ("block-set", Cst(arr: Array[Any]), Cst(i: Int), Cst(x)) => memory(sp) = Cst(arr(i) = x)
     case _ => BUG(s"ternary operator $op undefined")
   }
 
@@ -353,9 +368,9 @@ class StackInterpreter extends Interpreter with BugReporter {
    * an empty environment and return the value.
    */
   def run(exp: Exp): Val = {
-    // Start at 2, putchar and getchar are store at 0 and 1!!
-    eval(exp, 2)(LocationEnv())
-    memory(2)
+    // Start at 4, putchar, getchar, toChar, toInt are store at 0 and 1, 2, 3!!
+    eval(exp, 4)(LocationEnv())
+    memory(4)
   }
 
   /*
@@ -405,11 +420,47 @@ class StackInterpreter extends Interpreter with BugReporter {
         eval(cond, sp)(env)
       }
       eval(body, sp)(env)
-    case FunDef(_, args, _, fbody) => ???
+    case FunDef(_, args, _, fbody) => 
+      memory(sp) = Func(args map { arg => (arg.name) }, fbody, env)
     case LetRec(funs, body) =>
       // TODO modify that code
-      eval(body, sp)(env)
-    case App(fun, args) => ???
-    case ArrayDec(size, _) => ???
+      val ids = (sp until sp + funs.length).toList
+      // Evaluate all functions
+      val funcs = (funs zip ids) map { case (fun@FunDef(name, _, _, _), idx) => (name, idx) }
+      
+      // Add all functions to the functions environment (recursion)
+      (funs zip ids) foreach { case (fun@FunDef(_, _, _, _), idx:Int) => eval(fun, idx)(env.withVals(funcs)) }
+
+      eval(body, sp + funs.length)(env.withVals(funcs))
+      memory(sp) = memory(sp + funs.length)
+    
+    case App(fun, args) => 
+      val ids = (sp until sp + args.length).toList
+
+      (args zip ids) map { case (arg, idx) => eval(arg, idx)(env) }
+
+      eval(fun, sp + args.length)(env)
+      memory(sp + args.length) match {
+        case Func(fargs, fbody, fenv) =>
+          eval(fbody, sp + args.length + 1)(fenv.withVals(fargs zip ids))
+          memory(sp) = memory(sp + args.length + 1)
+        case Primitive("getchar") => 
+          memory(sp) = Cst(Console.in.read)
+        case Primitive("putchar") =>
+          val List(Cst(c: Int)) = memory(sp)
+          Console.out.write(c)
+          Console.out.flush
+          Cst(())
+        case Primitive("toInt") => 
+          val List(Cst(c: Char)) = memory(sp)
+          memory(sp) = Cst(c.toInt)
+        case Primitive("toChar") => 
+          val List(Cst(c: Int)) = memory(sp)
+          memory(sp) = Cst(c.toChar)
+      }
+    case ArrayDec(size, _) => 
+      eval(size, sp)(env)
+      val Cst(idx: Int) = memory(sp)
+      memory(sp) = Cst(new Array[Any](idx))
   }
 }
diff --git a/proj3/src/main/scala/project3/Main.scala b/proj3/src/main/scala/project3/Main.scala
index 4a40ae6..ada15f3 100644
--- a/proj3/src/main/scala/project3/Main.scala
+++ b/proj3/src/main/scala/project3/Main.scala
@@ -41,7 +41,6 @@ OPTION: intStack""")
     } else {
       args(0)
     }
-
     println("============ SRC CODE ============")
     println(src)
     println("==================================\n")
@@ -51,7 +50,7 @@ OPTION: intStack""")
 
     // Parser to test!
     // TODO: Change this as you finish parsers
-    val parser = new BaseParser(scanner)
+    val parser = new ArrayParser(scanner)
     val ast = try {
       parser.parseCode
     } catch {
diff --git a/proj3/src/main/scala/project3/Parser.scala b/proj3/src/main/scala/project3/Parser.scala
index 417eb2d..d36c614 100644
--- a/proj3/src/main/scala/project3/Parser.scala
+++ b/proj3/src/main/scala/project3/Parser.scala
@@ -99,11 +99,11 @@ class Scanner(in: Reader[Char]) extends Reader[Tokens.Token] with Reporter {
 
   // List of delimiters
   // TODO: Update this as delimiters are added to our language
-  val isDelim      = Set('(',')','=',';','{','}',':')
+  val isDelim      = Set('(',')','=',';','{','}',':', ',', '[', ']')
 
   // List of keywords
   // TODO: Update this as keywords are added to our language
-  val isKeyword    = Set("if", "else", "val", "var", "while")
+  val isKeyword    = Set("if", "else", "val", "var", "while", "def", "=>", "new")
 
   val isBoolean = Set("true", "false")
 
@@ -119,7 +119,7 @@ class Scanner(in: Reader[Char]) extends Reader[Tokens.Token] with Reporter {
     }
     val s = buf.toString
     if (isKeyword(s)) Keyword(s)
-    else if (isBoolean(s)) Boolean(s)
+    else if (isBoolean(s)) Literal(s.toBoolean)
     else Ident(s)
   }
 
@@ -169,6 +169,12 @@ class Scanner(in: Reader[Char]) extends Reader[Tokens.Token] with Reporter {
       getOperator()
     } else if (in.hasNext(isDigit)) {
       getNum()
+    } else if (in.hasNext(Set('\''))) {
+      in.next()
+      val s = in.next()
+      if (in.hasNext(_ == '\'')) in.next()
+      else expected(s"\'")
+      Literal(s)
     } else if (in.hasNext(isDelim)) {
       Delim(in.next())
     } else if (!in.hasNext) {
@@ -372,6 +378,7 @@ object Language {
   case class ArrayType(tp: Type) extends Type
 
   val IntType = BaseType("Int")
+  val CharType = BaseType("Char")
   val UnitType = BaseType("Unit")
   val BooleanType = BaseType("Boolean")
 
@@ -448,6 +455,18 @@ class BaseParser(in: Scanner) extends Parser(in) {
    * TODO: Implement this function
    */
   def parseType: Type = in.peek match {
+    case Ident("Int") =>
+      in.next()
+      IntType
+    case Ident("Char") => 
+      in.next()
+      CharType
+    case Ident("Boolean") => 
+      in.next()
+      BooleanType
+    case Ident("Unit") => 
+      in.next()
+      UnitType
     case _ => expected("type")
   }
 
@@ -460,6 +479,9 @@ class BaseParser(in: Scanner) extends Parser(in) {
    * TODO: Implement this function
    */
   def parseOptionalType: Type = in.peek match {
+    case Delim(':') => 
+      in.next()
+      parseType
     case _ => UnknownType
   }
 
@@ -626,14 +648,37 @@ class SyntacticSugarParser(in: Scanner) extends BaseParser(in) {
     suf + "$" + next
   }
 
-  override def parseSimpleExpression = in.peek match {
+  override def parseSimpleExpression = in.peek match { // !!!
+    case Keyword("if") =>
+        val pos = in.next().pos
+        accept('(')
+        val cond = parseSimpleExpression
+        accept(')')
+        val tBranch = parseSimpleExpression
+        val res = if (in.peek == Keyword("else")) {
+          in.next()
+          If(cond, tBranch, parseSimpleExpression).withPos(pos)
+        } else {
+          If(cond, tBranch, Lit(Unit)).withPos(pos)
+        }
+        res
     case _ => super.parseSimpleExpression
   }
 
   override def parseExpression = {
     // NOTE: parse expression terminates when it parse a simples expression.
-    // syntax sugar allows to have an other expression after it.
-    val res = super.parseExpression
+    // syntax sugar allows to have an other expression after it. !!!
+    var res = in.peek match {
+      case Keyword("val") | Keyword("var") | Keyword("while") =>
+        super.parseExpression
+      case _ => 
+        var simp = parseSimpleExpression
+        if(isNewLine(in.peek)) {
+          accept(';')
+          simp = Let(freshName(), UnknownType, simp, parseExpression).withPos(simp.pos)
+        }
+        simp
+    }
     res
   }
 
@@ -719,10 +764,30 @@ class FunctionParser(in: Scanner) extends SyntacticSugarParser(in) {
   /*
    * This function parse types.
    *
-   * TODO
+   * TODO !!!
    */
   override def parseType = in.peek match {
-    case _ => super.parseType
+   case Delim('(') =>
+      accept('(')
+      val list = parseList[Type](parseType, ',', tok => tok match {
+        case Delim(')') => false;
+        case _ => true
+      })
+      val argList = list map { tp => ("", tp)}
+      accept("=>")
+      val rtp = parseType
+      FunType(argList, rtp)
+    case _ => 
+    val typ = super.parseType
+    if(in.peek == Delim('=') && in.peek1 == Ident(">")) {
+      accept("=>")
+      val rtp = super.parseType
+      val typList: List[(String, Type)] = List(("", typ))
+      FunType(typList, rtp)
+    } 
+    else {
+      typ
+    }
   }
 
   /*
@@ -742,7 +807,9 @@ class FunctionParser(in: Scanner) extends SyntacticSugarParser(in) {
    * TODO: complete the function
    */
   def parseArg: Arg = {
-    ???
+    val (arg, pos) = getName()
+    val ty = parseOptionalType
+    Arg(arg, ty, pos)
   }
 
   /*
@@ -752,7 +819,16 @@ class FunctionParser(in: Scanner) extends SyntacticSugarParser(in) {
    * TODO: complete the function
    */
   def parseFunction: Exp = {
-    ???
+    accept("def")
+    val (fname, pos) = getName()
+    accept('(')
+    val args = parseList[Arg](parseArg, ',', _ match {
+      case Ident(_) => true; case _ => false 
+    })
+    accept(')')
+    val retTy = parseOptionalType
+    accept('=')
+    FunDef(fname, args, retTy, parseSimpleExpression).withPos(pos)
   }
 
   /*
@@ -765,6 +841,12 @@ class FunctionParser(in: Scanner) extends SyntacticSugarParser(in) {
    * TODO: complete the function
    */
   def parseProgram = in.peek match {
+    case Keyword("def") => 
+      val fns = parseList[Exp](parseFunction, ';', _ match {
+        case Keyword("def") => true; case _ => false
+      })
+      accept(';')
+      LetRec(fns, parseExpression)
     case _ => LetRec(Nil, parseExpression)
   }
 
@@ -798,7 +880,15 @@ class FunctionParser(in: Scanner) extends SyntacticSugarParser(in) {
       res
     case  _ =>
       var res = parseAtom
-      // TODO: complete
+      while(in.peek == Delim('(')) {
+        val pos = in.next().pos
+        val params = parseList[Exp](parseSimpleExpression, ',', _ match {
+          case Delim(')') => false; case _ => true
+        })
+        accept(')')
+        res = App(res, params).withPos(pos)
+      }
+      // Done: completed
       res
   }
 
@@ -865,7 +955,12 @@ class ArrayParser(in: Scanner) extends FunctionParser(in) {
   import Tokens._
 
   override def parseType = in.peek match {
-    case Ident("Array") => ???
+    case Ident("Array") => 
+      in.next()
+      accept('[')
+      val ty = parseType
+      accept(']')
+      ArrayType(ty)
     case _ => super.parseType
   }
 
@@ -874,12 +969,37 @@ class ArrayParser(in: Scanner) extends FunctionParser(in) {
    *
    * TODO
    */
-  override def parseTight = ???
+  override def parseTight : Exp = {
+    val lhs = super.parseTight
+    if (in.peek == Delim('=')) {
+      accept('=')
+      lhs match  {
+        case App(arr, List(idx)) =>
+          Prim("block-set", List(arr, idx, parseSimpleExpression)).withPos(lhs.pos)
+        case _ => 
+          error("Unsupported assignment")
+          lhs
+      }
+    }
+    else 
+      lhs
+  }
 
   /*
    * Parse array declaration
    *
    * TODO
    */
-  override def parseSimpleExpression = ???
+  override def parseSimpleExpression = in.peek match {
+    case Keyword("new") => 
+      val pos = in.next().pos
+      val ty = parseType
+      accept('(')
+      val expr = parseSimpleExpression
+      accept(')')
+      ArrayDec(expr, ty).withPos(pos)
+    case _ => 
+      super.parseSimpleExpression
+
+  }
 }
diff --git a/proj3/src/main/scala/project3/SemanticAnalyzer.scala b/proj3/src/main/scala/project3/SemanticAnalyzer.scala
index 3e4901f..ae70955 100644
--- a/proj3/src/main/scala/project3/SemanticAnalyzer.scala
+++ b/proj3/src/main/scala/project3/SemanticAnalyzer.scala
@@ -7,6 +7,8 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
    * Primitive functions that do not need to be defined or declared.
    */
   val primitives = Map[String,(Boolean,Type)](
+      "toInt" -> (false, FunType(List(("", CharType)), IntType)),
+      "toChar" -> (false, FunType(List(("", IntType)), CharType)),
       "getchar" -> (false, FunType(List(), IntType)),
       "putchar" -> (false, FunType(List(("", IntType)), UnitType))
     )
@@ -163,7 +165,10 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
    * TODO: implement the remaining binary operators for typeBinOperator
    */
   def typeBinOperator(op: String)(pos: Position) = op match {
-    case "+" => FunType(List(("", IntType), ("", IntType)), IntType)
+    case "+" | "-" | "*" | "/" => 
+      FunType(List(("", IntType), ("", IntType)), IntType)
+    case ">=" | "<=" | ">" | "<" | "==" | "!=" => 
+      FunType(List(("", IntType), ("", IntType)), BooleanType)
     case _ =>
       error("undefined binary operator", pos)
       UnknownType
@@ -177,6 +182,8 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
    * TODO: implement typeUnOperator
    */
   def typeUnOperator(op: String)(pos: Position) = op match {
+    case "+" | "-" => FunType(List(("", IntType)), IntType)
+//    case "!" => FunType(List(("", BooleanType)), BooleanType)
     case _ =>
       error(s"undefined unary operator", pos)
       UnknownType
@@ -188,6 +195,8 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
    * operators: block-set
    */
   def typeTerOperator(op: String)(pos: Position) = op match {
+    case "block-set" => 
+      FunType(List(("", ArrayType(IntType)), ("", IntType)), IntType)
     case _ =>
       error(s"undefined ternary operator", pos)
       UnknownType
@@ -215,7 +224,8 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
     case (_, UnknownType) => typeWellFormed(tp)(env, pos)  // tp <: Any
     case (UnknownType, _) => typeWellFormed(pt)(env, pos)  // for function arguments
     case (FunType(args1, rtp1), FunType(args2, rtp2)) if args1.length == args2.length => 
-      ??? // TODO: Function type conformity
+      FunType(typeConform(args1, args2)(env, pos), typeConforms(rtp1, rtp2)(env, pos))
+      // Done: Function type conformity
     case (ArrayType(tp), ArrayType(pt)) => ArrayType(typeConforms(tp, pt)(env, pos))
     case _ => error(s"type mismatch;\nfound   : $tp\nexpected: $pt", pos); pt
   }
@@ -281,12 +291,22 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
 
   def typeInfer(exp: Exp, pt: Type)(env: TypeEnv): Exp = exp match {
     case Lit(_: Int) => exp.withType(IntType)
-    case Lit(_: Boolean) => ???
-    case Lit(_: Unit) => ???
-    case Prim("block-set", args) => ???
+    case Lit(_: Boolean) => exp.withType(BooleanType)
+    case Lit(_: Char) => exp.withType(CharType)
+    case Lit(_: Unit) => exp.withType(UnitType)
+    case Prim("block-set", args) => 
+      Prim("block-set", List(
+        typeCheck(args(0), ArrayType(pt))(env), 
+        typeCheck(args(1), IntType)(env), 
+        typeCheck(args(2), pt)(env)
+      )).withType(UnitType)
     case Prim(op, args) =>
       typeOperator(op, args.length)(exp.pos) match {
-        case FunType(atps, rtp) => ???
+        case FunType(atps, rtp) => 
+          val args_checked = (args zip atps) map {
+            case (arg, (_, param)) => typeCheck(arg, param)(env)
+          }
+          Prim(op, args_checked).withType(rtp)
         case UnknownType => exp.withType(UnknownType)
         case _ => BUG("operator's type needs to be FunType")
       }
@@ -298,18 +318,28 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
       Let(x, nrhs.tp, nrhs, nbody).withType(nbody.tp)
     case Ref(x) =>
       env(x) match {
-        case Some(tp) => ??? // Remember to check that the type taken from the environment is welformed
+        case Some(tp) => 
+          exp.withType(typeWellFormed(tp)(env, exp.pos))
+          // Remember to check that the type taken from the environment is wellformed
         case _ =>
           error("undefined identifier", exp.pos)
-          ???
+          exp.withType(UnknownType)
       }
     case If(cond, tBranch, eBranch) =>
       // Hint: type check the else branch before the then branch.
-      ???
+      val condChecked = typeCheck(cond, BooleanType)(env) 
+      val elseChecked = typeCheck(eBranch, pt)(env)
+      val thenChecked = typeCheck(tBranch, elseChecked.tp)(env)
+      If(condChecked, thenChecked, elseChecked).withType(elseChecked.tp)
+
     case VarDec(x, tp, rhs, body) =>
       if (env.isDefined(x))
         warn("reuse of variable name", exp.pos)
-      ???
+      val rhsChecked = typeCheck(rhs, tp)(env)
+      val _env = env.withVar(x, rhsChecked.tp)
+      val bodyChecked = typeCheck(body, pt)(_env)
+      VarDec(x, rhsChecked.tp, rhsChecked, bodyChecked).withType(bodyChecked.tp)
+
     case VarAssign(x, rhs) =>
       val xtp = if (!env.isDefined(x)) {
         error("undefined identifier", exp.pos)
@@ -320,7 +350,7 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
         env(x).get
       }
 
-      ???
+      val rhsChecked = typeCheck(rhs, xtp)(env)
 
       /* Because of syntactic sugar, a variable assignment 
        * statement can be accepted as an expression
@@ -338,18 +368,35 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
        * Without changing the semantics!
        */
       pt match {
-        case UnitType => ???
-        case _ => ???
+        case UnitType | IntType | BooleanType | CharType => VarAssign(x, rhsChecked).withType(rhsChecked.tp)
+        case _ => exp.withType(UnknownType)
+      }
+    case While(cond, lbody, body) => 
+      val condChecked = typeCheck(cond, BooleanType)(env)
+      val lbodyChecked = typeCheck(lbody, UnitType)(env)
+      val bodyChecked = typeCheck(body, pt)(env)
+      While(condChecked, lbodyChecked, bodyChecked).withType(bodyChecked.tp)
+
+    case FunDef(fname, args, rtp, fbody) => 
+      checkDuplicateNames(args)
+      val argsWType = args map {
+        a => (a.name, typeWellFormed(a.tp)(env, a.pos))
       }
-    case While(cond, lbody, body) => ???
-    case FunDef(fname, args, rtp, fbody) => ???
+      val bodyChecked = typeCheck(fbody, rtp)(env.withVals(argsWType)) // check rtp w/ pt?
+      FunDef(fname, args, bodyChecked.tp, bodyChecked).withType(
+        FunType(argsWType, bodyChecked.tp)
+      )
+
     case LetRec(funs, body) =>
       // TODO modify to handle general case
-      val nbody = typeCheck(body, pt)(env)
-      LetRec(Nil, nbody).withType(nbody.tp)
+      val _env = env.withVals(funs.map {case FunDef(name, _, rtp, _) => (name, rtp)})
+      val funsChecked = funs map {case f@FunDef(_, _, rtp, _) => typeCheck(f, rtp)(_env) }
+      val bodyChecked = typeCheck(body, pt)( env.withVals(funsChecked map {case FunDef(name, _, rtp, _) => (name, rtp)}))
+      LetRec(funsChecked, bodyChecked).withType(bodyChecked.tp)
+
     case App(fun, args) =>
       // TODO Check fun type
-      val nFun: Exp = ???
+      val nFun: Exp = typeCheck(fun, fun.tp)(env)
 
       // Handling some errors
       val ftp = nFun.tp match {
@@ -369,7 +416,9 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
       }
 
       // TODO: Check arguments type
-      val nargs: List[Exp] = ???
+      val nargs: List[Exp] = (args zip ftp.args) map {
+        case (arg, (_, param)) => typeCheck(arg, param)(env)
+      }
 
       // Transform some function applications into primitives on arrays.
       nFun.tp match {
@@ -380,7 +429,7 @@ class SemanticAnalyzer(parser: Parser) extends Reporter with BugReporter {
     case ArrayDec(size: Exp, etp: Type) => 
       // TODO: Check array declaration
       // Note that etp is the type of elements
-      ???
+      ArrayDec(typeCheck(size, IntType)(env), etp).withType(etp)
     case _ => BUG(s"malformed expresstion $exp")
   }
 }