afl-material: comparison progs/parser-combinators/comb2-simple.sc

equal deleted inserted replaced

-:b7d97a2a083b
+:1544a674dd35
 // call with
 //
 //    amm comb2-simple.sc
+// to make sure the input has an empty-method
 trait IsSeq[I] {
 extension (i: I) def isEmpty: Boolean
 }
 given IsSeq[String] = _.isEmpty
 // an interpreter for the WHILE language
 type Env = Map[String, Int]
-def eval_aexp(a: AExp, env: Env) : Int =
+def eval_aexp(a: AExp, env: Env) : Int = a match {
-a match {
 case Num(i) => i
 case Var(s) => env(s)
 case Aop("+", a1, a2) => eval_aexp(a1, env) + eval_aexp(a2, env)
 case Aop("-", a1, a2) => eval_aexp(a1, env) - eval_aexp(a2, env)
 case Aop("*", a1, a2) => eval_aexp(a1, env) * eval_aexp(a2, env)
 case Aop("/", a1, a2) => eval_aexp(a1, env) / eval_aexp(a2, env)
 }
-def eval_bexp(b: BExp, env: Env) : Boolean =
+def eval_bexp(b: BExp, env: Env) : Boolean = b match {
-b match {
 case True => true
 case False => false
 case Bop("==", a1, a2) => eval_aexp(a1, env) == eval_aexp(a2, env)
 case Bop("!=", a1, a2) => !(eval_aexp(a1, env) == eval_aexp(a2, env))
 case Bop(">", a1, a2) => eval_aexp(a1, env) > eval_aexp(a2, env)
 case Bop("<", a1, a2) => eval_aexp(a1, env) < eval_aexp(a2, env)
 case And(b1, b2) => eval_bexp(b1, env) && eval_bexp(b2, env)
 case Or(b1, b2) => eval_bexp(b1, env) || eval_bexp(b2, env)
 }
-def eval_stmt(s: Stmt, env: Env) : Env =
+def eval_stmt(s: Stmt, env: Env) : Env = s match {
-s match {
 case Skip => env
 case Assign(x, a) => env + (x -> eval_aexp(a, env))
 case If(b, bl1, bl2) => if (eval_bexp(b, env)) eval_bl(bl1, env) else eval_bl(bl2, env)
 case While(b, bl) =>
 if (eval_bexp(b, env)) eval_stmt(While(b, bl), eval_bl(bl, env))
 else env
 case Write(x) => { println(env(x)) ; env }
 }
-def eval_bl(bl: Block, env: Env) : Env =
+def eval_bl(bl: Block, env: Env) : Env = bl match {
-bl match {
 case Nil => env
 case s::bl => eval_bl(bl, eval_stmt(s, env))
 }
 def eval(bl: Block) : Env = eval_bl(bl, Map())

changeset 972	1544a674dd35
parent 971	b7d97a2a083b