--- a/progs/mllex.scala	Mon Jul 27 11:02:48 2020 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,109 +0,0 @@
-:load matcher.scala
-
-
-// some regular expressions
-val KEYWORDS =  ALTS(List("#", "(", ")", ",", "->", "...", ":", ":>", ";", "=",
-  "=>", "[", "]", "_", "{", "|", "}", "abstype", "and", "andalso", "as",
-  "case", "datatype", "do", "else", "end", "eqtype", "exception", "fn",
-  "fun", "functor", "handle", "if", "in", "include", "infix", "infixr",
-  "let", "local", "nonfix", "of", "op", "open", "orelse", "raise", "rec",
-  "sharing", "sig", "signature", "struct", "structure", "then", "type",
-  "val", "where", "while", "with", "withtype"))
-
-val DIGITS = RANGE("0123456789")
-val NONZERODIGITS = RANGE("123456789")
-
-val POSITIVES = ALT(SEQ(NONZERODIGITS, STAR(DIGITS)), "0")
-val INTEGERS = ALT(SEQ("~", POSITIVES), POSITIVES)
-
-val ALL = ALTS(KEYWORDS, INTEGERS)
-
-val COMMENT = SEQS("/*", NOT(SEGS(STAR(ALL), "*/", STAR(ALL))), "*/")
-
-
-
-val LPAREN = CHAR('(')
-val RPAREN = CHAR(')')
-val WHITESPACE = PLUS(RANGE(" \n".toList))
-val OPS = RANGE("+-*".toList)
-
-// for classifying the strings that have been recognised
-abstract class Token
-case object T_WHITESPACE extends Token
-case object T_NUM extends Token
-case class T_OP(s: String) extends Token
-case object T_LPAREN extends Token
-case object T_RPAREN extends Token
-case class T_NT(s: String, rhs: List[Token]) extends Token
-
-def tokenizer(rs: List[Rule[Token]], s: String) : List[Token] = 
-  tokenize(rs, s.toList).filterNot(_ match {
-    case T_WHITESPACE => true
-    case _ => false
-  })
-
-
-
-// lexing rules for arithmetic expressions
-val lexing_rules: List[Rule[Token]]= 
-  List((NUMBER, (s) => T_NUM),
-       (WHITESPACE, (s) => T_WHITESPACE),
-       (LPAREN, (s) => T_LPAREN),
-       (RPAREN, (s) => T_RPAREN),
-       (OPS, (s) => T_OP(s.mkString)))
-
-tokenize_file(Nil, "nominal_library.ML")
-
-
-
-
-type Grammar = List[(String, List[Token])]
-
-// grammar for arithmetic expressions
-val grammar = 
-  List ("E" -> List(T_NUM),
-        "E" -> List(T_NT("E", Nil), T_OP("+"), T_NT("E", Nil)),
-        "E" -> List(T_NT("E", Nil), T_OP("-"), T_NT("E", Nil)),
-        "E" -> List(T_NT("E", Nil), T_OP("*"), T_NT("E", Nil)),    
-        "E" -> List(T_LPAREN, T_NT("E", Nil), T_RPAREN))
-
-def startsWith[A](ts1: List[A], ts2: List[A]) : Boolean = (ts1, ts2) match {
-  case (_, Nil) => true
-  case (T_NT(e, _)::ts1,T_NT(f, _)::ts2) => (e == f) && startsWith(ts1, ts2)
-  case (t1::ts1, t2::ts2) => (t1 == t2) && startsWith(ts1, ts2)
-  case _ => false
-}
-
-def chop[A](ts1: List[A], prefix: List[A], ts2: List[A]) : Option[(List[A], List[A])] = 
-  ts1 match {
-    case Nil => None
-    case t::ts => 
-      if (startsWith(ts1, prefix)) Some(ts2.reverse, ts1.drop(prefix.length))
-      else chop(ts, prefix, t::ts2)
-  }
-
-// examples
-chop(List(1,2,3,4,5,6,7,8,9), List(4,5), Nil)  
-chop(List(1,2,3,4,5,6,7,8,9), List(3,5), Nil)  
-
-def replace[A](ts: List[A], out: List[A], in: List [A]) = 
-  chop(ts, out, Nil) match {
-    case None => None
-    case Some((before, after)) => Some(before ::: in ::: after)
-  }  
-
-def parse1(g: Grammar, ts: List[Token]) : Boolean = ts match {
-  case List(T_NT("E", tree)) => { println(tree); true }
-  case _ => {
-    val tss = for ((lhs, rhs) <- g) yield replace(ts, rhs, List(T_NT(lhs, rhs)))
-    tss.flatten.exists(parse1(g, _))
-  }
-}
- 
-
-println() ; parse1(grammar, tokenizer(lexing_rules, "2 + 3 * 4 + 1"))
-println() ; parse1(grammar, tokenizer(lexing_rules, "(2 + 3) * (4 + 1)"))
-println() ; parse1(grammar, tokenizer(lexing_rules, "(2 + 3) * 4 (4 + 1)"))
-
-
-