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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))
}
}
|
