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Diffstat (limited to 'docs/examples/parsing/MiniML.scala')
-rw-r--r-- | docs/examples/parsing/MiniML.scala | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/docs/examples/parsing/MiniML.scala b/docs/examples/parsing/MiniML.scala new file mode 100644 index 0000000000..ffc7c2ac92 --- /dev/null +++ b/docs/examples/parsing/MiniML.scala @@ -0,0 +1,52 @@ +package examples.parsing + +import scala.util.parsing.combinator1.syntactical.StandardTokenParsers +import scala.util.parsing.combinator1.syntactical.StandardTokenParsers + +object MiniML extends StandardTokenParsers { + lexical.delimiters += ("(", ")", ".", "=") + lexical.reserved += ("lambda", "let", "in") + + def expr: Parser[Any] = ( + "let" ~ ident ~ "=" ~ expr ~ "in" ~ expr + | "lambda" ~ ident ~ "." ~ expr + | simpleExpr ~ rep(expr) + ) + def simpleExpr: Parser[Any] = ( + ident + | "(" ~ expr ~ ")" + ) + + def main(args: Array[String]) { + val tokens = new lexical.Scanner(args(0)) + println(args(0)) + println(phrase(expr)(tokens)) + } +} + +class Expr +case class Let(x: String, expr: Expr, body: Expr) extends Expr +case class Lambda(x: String, expr: Expr) extends Expr +case class Apply(fun: Expr, arg: Expr) extends Expr +case class Var(x: String) extends Expr + +object MiniML1 extends StandardTokenParsers { + lexical.delimiters += ("(", ")", ".", "=") + lexical.reserved += ("lambda", "let", "in") + + def expr: Parser[Expr] = ( + "let" ~ ident ~ "=" ~ expr ~ "in" ~ expr ^^ { case "let" ~ x ~ "=" ~ e ~ "in" ~ b => Let(x, e, b) } + | "lambda" ~ ident ~ "." ~ expr ^^ { case "lambda" ~ x ~ "." ~ e => Lambda(x, e) } + | simpleExpr ~ rep(expr) ^^ { case f ~ as => (f /: as) (Apply) } + ) + def simpleExpr: Parser[Expr] = ( + ident ^^ { Var } + | "(" ~> expr <~ ")" + ) + + def main(args: Array[String]) { + val tokens = new lexical.Scanner(args(0)) + println(args(0)) + println(phrase(expr)(tokens)) + } +} |