diff -r 3b1136fb6bee -r f0696713177b progs/fun/funt.sc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/fun/funt.sc	Sun Oct 25 01:25:01 2020 +0000
@@ -0,0 +1,168 @@
+// A Small Compiler for a Simple Functional Language
+// (includes a lexer and a parser)
+
+import $file.fun_tokens, fun_tokens._
+import $file.fun_parser, fun_parser._ 
+
+// compiler - built-in functions 
+// copied from http://www.ceng.metu.edu.tr/courses/ceng444/link/jvm-cpm.html
+//
+
+val library = """
+.class public XXX.XXX
+.super java/lang/Object
+
+.method public static write(I)V 
+        .limit locals 1 
+        .limit stack 2 
+        getstatic java/lang/System/out Ljava/io/PrintStream; 
+        iload 0
+        invokevirtual java/io/PrintStream/println(I)V 
+        return 
+.end method
+
+"""
+
+// calculating the maximal needed stack size
+def max_stack_exp(e: Exp): Int = e match {
+  case Call(_, args) => args.map(max_stack_exp).sum
+  case If(a, e1, e2) => max_stack_bexp(a) + (List(max_stack_exp(e1), max_stack_exp(e2)).max)
+  case Write(e) => max_stack_exp(e) + 1
+  case Var(_) => 1
+  case Num(_) => 1
+  case Aop(_, a1, a2) => max_stack_exp(a1) + max_stack_exp(a2)
+  case Sequence(e1, e2) => List(max_stack_exp(e1), max_stack_exp(e2)).max
+}
+
+def max_stack_bexp(e: BExp): Int = e match {
+  case Bop(_, a1, a2) => max_stack_exp(a1) + max_stack_exp(a2)
+}
+
+
+// for generating new labels
+var counter = -1
+
+def Fresh(x: String) = {
+  counter += 1
+  x ++ "_" ++ counter.toString()
+}
+
+// convenient string interpolations 
+// for instructions, labels and methods
+import scala.language.implicitConversions
+import scala.language.reflectiveCalls
+
+implicit def sring_inters(sc: StringContext) = new {
+    def i(args: Any*): String = "   " ++ sc.s(args:_*) ++ "\n"
+    def l(args: Any*): String = sc.s(args:_*) ++ ":\n"
+    def m(args: Any*): String = sc.s(args:_*) ++ "\n"
+}
+
+
+type Env = Map[String, Int]
+
+
+def compile_expT(a: Exp, env : Env, name: String) : String = a match {
+  case Num(i) => i"ldc $i"
+  case Var(s) => i"iload ${env(s)}"
+  case Aop("+", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"iadd"
+  case Aop("-", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"isub"
+  case Aop("*", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"imul"
+  case Aop("/", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"idiv"
+  case Aop("%", a1, a2) => compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"irem"
+  case If(b, a1, a2) => {
+    val if_else = Fresh("If_else")
+    val if_end = Fresh("If_end")
+    compile_bexpT(b, env, if_else) ++
+    compile_expT(a1, env, name) ++
+    i"goto $if_end" ++
+    l"$if_else" ++
+    compile_expT(a2, env, name) ++
+    l"$if_end"
+  }
+  case Call(n, args) => if (name == n) { 
+    val stores = args.zipWithIndex.map { case (x, y) => i"istore $y" } 
+    args.map(a => compile_expT(a, env, "")).mkString ++
+    stores.reverse.mkString ++ 
+    i"goto ${n}_Start" 
+  } else {
+    val is = "I" * args.length
+    args.map(a => compile_expT(a, env, "")).mkString ++
+    i"invokestatic XXX/XXX/${n}(${is})I"
+  }
+  case Sequence(a1, a2) => {
+    compile_expT(a1, env, "") ++ i"pop" ++ compile_expT(a2, env, name)
+  }
+  case Write(a1) => {
+    compile_expT(a1, env, "") ++
+    i"dup" ++
+    i"invokestatic XXX/XXX/write(I)V"
+  }
+}
+
+def compile_bexpT(b: BExp, env : Env, jmp: String) : String = b match {
+  case Bop("==", a1, a2) => 
+    compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"if_icmpne $jmp"
+  case Bop("!=", a1, a2) => 
+    compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"if_icmpeq $jmp"
+  case Bop("<", a1, a2) => 
+    compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"if_icmpge $jmp"
+  case Bop("<=", a1, a2) => 
+    compile_expT(a1, env, "") ++ compile_expT(a2, env, "") ++ i"if_icmpgt $jmp"
+}
+
+
+def compile_decl(d: Decl) : String = d match {
+  case Def(name, args, a) => { 
+    val env = args.zipWithIndex.toMap
+    val is = "I" * args.length
+    m".method public static $name($is)I" ++
+    m".limit locals ${args.length}" ++
+    m".limit stack ${1 + max_stack_exp(a)}" ++
+    l"${name}_Start" ++   
+    compile_expT(a, env, name) ++
+    i"ireturn" ++ 
+    m".end method\n"
+  }
+  case Main(a) => {
+    m".method public static main([Ljava/lang/String;)V" ++
+    m".limit locals 200" ++
+    m".limit stack 200" ++
+    compile_expT(a, Map(), "") ++
+    i"invokestatic XXX/XXX/write(I)V" ++
+    i"return" ++
+    m".end method"
+  }
+}
+
+// main compiler functions
+def compile(prog: List[Decl], class_name: String) : String = {
+  val instructions = prog.map(compile_decl).mkString
+  (library + instructions).replaceAllLiterally("XXX", class_name)
+}
+
+
+@main
+def main(fname: String) = {
+    val path = os.pwd / fname
+    val class_name = fname.stripSuffix("." ++ path.ext)
+    val tks = tokenise(os.read(path))
+    val ast = parse_tks(tks)
+    println(compile(ast, class_name))
+}
+
+/*
+
+import scala.sys.process._
+
+def compile_run(class_name: String) : Unit = {
+  compile_file(class_name)
+  (s"java -jar jvm/jasmin-2.4/jasmin.jar ${class_name}.j").!!
+  println("Time: " + time_needed(2, (s"java ${class_name}/${class_name}").!))
+}
+
+
+//examples
+compile_run("defs")
+compile_run("fact")
+*/