combinator1 parser changes + examples added

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))
+  }
+}