diff -r 908e4f6cdf7c -r 4d5058706f1b solution/cw5/fun_parser.sc
--- a/solution/cw5/fun_parser.sc	Fri Oct 28 09:08:13 2022 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,215 +0,0 @@
-// A parser for the Fun language
-//================================
-//
-// call with 
-//
-//     amm fun_parser.sc fact.fun
-//
-//     amm fun_parser.sc defs.fun
-//
-// this will generate a parse-tree from a list
-// of tokens
-
-import scala.language.implicitConversions    
-import scala.language.reflectiveCalls
-
-import $file.fun_tokens, fun_tokens._ 
-
-
-// Parser combinators
-//    type parameter I needs to be of Seq-type
-//
-abstract class Parser[I, T](implicit ev: I => Seq[_]) {
-  def parse(ts: I): Set[(T, I)]
-
-  def parse_single(ts: I) : T = 
-    parse(ts).partition(_._2.isEmpty) match {
-      case (good, _) if !good.isEmpty => good.head._1
-      case (good, err) if err.isEmpty => {
-        println (s"Parse Error\n $good \n $err") ; sys.exit(-1) }
-      case (_, err) => { 
-	println (s"Parse Error\n${err.minBy(_._2.length)}") ; sys.exit(-1) }
-    }
-}
-
-// convenience for writing grammar rules
-case class ~[+A, +B](_1: A, _2: B)
-
-class SeqParser[I, T, S](p: => Parser[I, T], 
-                         q: => Parser[I, S])(implicit ev: I => Seq[_]) extends Parser[I, ~[T, S]] {
-  def parse(sb: I) = 
-    for ((head1, tail1) <- p.parse(sb); 
-         (head2, tail2) <- q.parse(tail1)) yield (new ~(head1, head2), tail2)
-}
-
-class AltParser[I, T](p: => Parser[I, T], 
-                      q: => Parser[I, T])(implicit ev: I => Seq[_]) extends Parser[I, T] {
-  def parse(sb: I) = p.parse(sb) ++ q.parse(sb)   
-}
-
-class FunParser[I, T, S](p: => Parser[I, T], 
-                         f: T => S)(implicit ev: I => Seq[_]) extends Parser[I, S] {
-  def parse(sb: I) = 
-    for ((head, tail) <- p.parse(sb)) yield (f(head), tail)
-}
-
-// convenient combinators
-implicit def ParserOps[I, T](p: Parser[I, T])(implicit ev: I => Seq[_]) = new {
-  def || (q : => Parser[I, T]) = new AltParser[I, T](p, q)
-  def ==>[S] (f: => T => S) = new FunParser[I, T, S](p, f)
-  def ~[S] (q : => Parser[I, S]) = new SeqParser[I, T, S](p, q)
-}
-
-def ListParser[I, T, S](p: => Parser[I, T], 
-                        q: => Parser[I, S])(implicit ev: I => Seq[_]): Parser[I, List[T]] = {
-  (p ==> ((s) => List(s))) ||
-  (p ~ q ~ ListParser(p, q)) ==> { case x ~ _ ~ z => x :: z : List[T] }
-}
-
-case class TokParser(tok: Token) extends Parser[List[Token], Token] {
-  def parse(ts: List[Token]) = ts match {
-    case t::ts if (t == tok) => Set((t, ts)) 
-    case _ => Set()
-  }
-}
-
-implicit def token2tparser(t: Token) = TokParser(t)
-
-implicit def TokOps(t: Token) = new {
-  def || (q : => Parser[List[Token], Token]) = new AltParser[List[Token], Token](t, q)
-  def ==>[S] (f: => Token => S) = new FunParser[List[Token], Token, S](t, f)
-  def ~[S](q : => Parser[List[Token], S]) = new SeqParser[List[Token], Token, S](t, q)
-}
-
-case object EmptyParser extends Parser[List[Token], String] {
-  def parse(ts: List[Token]) = Set(("", ts))
-}
-
-case object NumParser extends Parser[List[Token], Int] {
-  def parse(ts: List[Token]) = ts match {
-    case T_NUM(n)::ts => Set((n, ts)) 
-    case _ => Set ()
-  }
-}
-
-case object FNumParser extends Parser[List[Token], Double] {
-  def parse(ts: List[Token]) = ts match {
-    case T_FNUM(x)::ts => Set((x, ts)) 
-    case _ => Set()
-  }
-}
-
-case object IdParser extends Parser[List[Token], String] {
-  def parse(ts: List[Token]) = ts match {
-    case T_ID(s)::ts => Set((s, ts)) 
-    case _ => Set ()
-  }
-}
-
-case object CharConstParser extends Parser[List[Token], Int] {
-  def parse(ts: List[Token]) = ts match {
-    case T_CHR(c)::ts => Set((c, ts)) 
-    case _ => Set ()
-  }
-}
-
-case object TyParser extends Parser[List[Token], String] {
-  def parse(ts: List[Token]) = ts match {
-    case T_TY(s)::ts => Set((s, ts)) 
-    case _ => Set ()
-  }
-}
-
-
-// Abstract syntax trees for the Fun language
-abstract class Exp 
-abstract class BExp 
-abstract class Decl 
-
-case class Def(name: String, args: List[(String, String)], ty: String, body: Exp) extends Decl
-case class Main(e: Exp) extends Decl
-case class Const(name: String, v: Int) extends Decl
-case class FConst(name: String, x: Double) extends Decl
-
-case class Call(name: String, args: List[Exp]) extends Exp
-case class If(a: BExp, e1: Exp, e2: Exp) extends Exp
-case class Var(s: String) extends Exp
-case class Num(i: Int) extends Exp     // integer numbers
-case class FNum(i: Double) extends Exp  // floating numbers
-case class ChConst(c: Int) extends Exp // char constant
-case class Aop(o: String, a1: Exp, a2: Exp) extends Exp
-case class Sequence(e1: Exp, e2: Exp) extends Exp
-case class Bop(o: String, a1: Exp, a2: Exp) extends BExp
-
-
-// arithmetic expressions (there needs to be an F in the SEMICOLON case)
-lazy val Exp: Parser[List[Token], Exp] = 
-  (T_KWD("if") ~ BExp ~ T_KWD("then") ~ Exp ~ T_KWD("else") ~ Exp) ==>
-    { case _ ~ x ~ _ ~ y ~ _ ~ z => If(x, y, z): Exp } ||
-  (F ~ T_SEMI ~ Exp) ==> { case x ~ _ ~ y => Sequence(x, y): Exp } || L
-lazy val L: Parser[List[Token], Exp] = 
-  (T ~ T_OP("+") ~ Exp) ==> { case x ~ _ ~ z => Aop("+", x, z): Exp } ||
-  (T ~ T_OP("-") ~ Exp) ==> { case x ~ _ ~ z => Aop("-", x, z): Exp } || T  
-lazy val T: Parser[List[Token], Exp] = 
-  (F ~ T_OP("*") ~ T) ==> { case x ~ _ ~ z => Aop("*", x, z): Exp } || 
-  (F ~ T_OP("/") ~ T) ==> { case x ~ _ ~ z => Aop("/", x, z): Exp } || 
-  (F ~ T_OP("%") ~ T) ==> { case x ~ _ ~ z => Aop("%", x, z): Exp } || F
-lazy val F: Parser[List[Token], Exp] = 
-  (IdParser ~ T_LPAREN ~ T_RPAREN) ==> { case x ~ _ ~ _ => Call(x, Nil): Exp } ||
-  (IdParser ~ T_LPAREN ~ ListParser(Exp, T_COMMA) ~ T_RPAREN) ==> { case x ~ _ ~ z ~ _ => Call(x, z): Exp } ||
-  (T_LPAREN ~ Exp ~ T_RPAREN) ==> { case _ ~ y ~ _ => y: Exp } || 
-  IdParser ==> { case x => Var(x): Exp } || 
-  NumParser ==> { case x => Num(x): Exp } ||
-  CharConstParser ==> { case x => ChConst(x): Exp } ||
-  FNumParser ==> { case x => FNum(x): Exp }
-
-// boolean expressions
-lazy val BExp: Parser[List[Token], BExp] = 
-  (Exp ~ T_OP("==") ~ Exp) ==> { case x ~ _ ~ z => Bop("==", x, z): BExp } || 
-  (Exp ~ T_OP("!=") ~ Exp) ==> { case x ~ _ ~ z => Bop("!=", x, z): BExp } || 
-  (Exp ~ T_OP("<") ~ Exp)  ==> { case x ~ _ ~ z => Bop("<",  x, z): BExp } || 
-  (Exp ~ T_OP(">") ~ Exp)  ==> { case x ~ _ ~ z => Bop("<",  z, x): BExp } || 
-  (Exp ~ T_OP("<=") ~ Exp) ==> { case x ~ _ ~ z => Bop("<=", x, z): BExp } || 
-  (Exp ~ T_OP("=>") ~ Exp) ==> { case x ~ _ ~ z => Bop("<=", z, x): BExp } ||
-  (T_LPAREN ~ BExp ~ T_RPAREN) ==> { case _ ~ b ~ _ => b : BExp } 
-
-lazy val Arg : Parser[List[Token], (String, String)] = 
-  (IdParser ~ T_COLON ~ TyParser) ==> { case x ~ _ ~ ty => (x, ty) }  
-
-lazy val Defn: Parser[List[Token], Decl] = {
-   (T_KWD("def") ~ IdParser ~ T_LPAREN ~ T_RPAREN ~ T_COLON ~ TyParser ~ T_OP("=") ~ Exp) ==>
-     { case _ ~ y ~ _ ~ _ ~ _~ ty ~ _ ~ r => Def(y, Nil, ty, r): Decl } ||
-   (T_KWD("def") ~ IdParser ~ T_LPAREN ~ ListParser(Arg, T_COMMA) ~ T_RPAREN ~ T_COLON ~ TyParser ~ T_OP("=") ~ Exp) ==>
-     { case _ ~ y ~ _ ~ w ~ _ ~ _~ ty ~ _ ~ r => Def(y, w, ty, r): Decl }
-}
-
-lazy val Const_decl: Parser[List[Token], Decl] =
-   (T_KWD("val") ~ Arg ~ T_OP("=") ~ NumParser) ==>
-     { case _ ~ x ~ _ ~ v => Const(x._1, v): Decl } ||
-   (T_KWD("val") ~ Arg ~ T_OP("=") ~ FNumParser) ==>
-     { case _ ~ x ~ _ ~ v => FConst(x._1, v): Decl } 
-
-lazy val Prog: Parser[List[Token], List[Decl]] =
-  (Defn ~ T_SEMI ~ Prog) ==> { case x ~ _ ~ z => x :: z : List[Decl] } ||
-  (Const_decl ~ T_SEMI ~ Prog) ==> { case x ~ _ ~ z => x :: z : List[Decl] } ||
-  (Exp ==> ((s) => List(Main(s)) : List[Decl]))
-
-
-
-// Reading tokens and Writing parse trees
-
-//import ammonite.ops._
-
-def parse_tks(tks: List[Token]) : List[Decl] = {
-  //println(Prog.parse(tks))
-  Prog.parse_single(tks)
-}
-
-//@doc("Parses a file.")
-@main
-def main(fname: String) : Unit = {
-  val tks = tokenise(os.read(os.pwd / fname))
-  println(parse_tks(tks))
-}
-
-