Merge branch 'master' into gh-pages

Conflicts:
	.gitignore

1 files changed, 73 insertions, 0 deletions

diff --git a/scala/step2_eval.scala b/scala/step2_eval.scala
new file mode 100644
index 0000000..d31d339
--- /dev/null
+++ b/scala/step2_eval.scala
@@ -0,0 +1,73 @@
+import types.{MalList, _list_Q, MalVector, MalHashMap, MalFunction}
+
+object step2_eval {
+  // read
+  def READ(str: String): Any = {
+    reader.read_str(str)
+  }
+
+  // eval
+  def eval_ast(ast: Any, env: Map[Symbol,Any]): Any = {
+    ast match {
+      case s : Symbol    => env(s)
+      case v: MalVector  => v.map(EVAL(_, env))
+      case l: MalList    => l.map(EVAL(_, env))
+      case m: MalHashMap => {
+        m.map{case (k: String,v: Any) => (k, EVAL(v, env))}
+      }
+      case _             => ast
+    }
+  }
+
+  def EVAL(ast: Any, env: Map[Symbol,Any]): Any = {
+    //println("EVAL: " + printer._pr_str(ast,true))
+    if (!_list_Q(ast))
+      return eval_ast(ast, env)
+
+    // apply list
+    eval_ast(ast, env).asInstanceOf[MalList].value match {
+      case f :: el => {
+        var fn: List[Any] => Any = null
+        try {
+          fn = f.asInstanceOf[List[Any] => Any]
+        } catch {
+          case _: Throwable =>
+            throw new Exception("attempt to call non-function")
+        }
+        return fn(el)
+      }
+      case _ => throw new Exception("invalid apply")
+    }
+  }
+
+  // print
+  def PRINT(exp: Any): String = {
+    printer._pr_str(exp, true)
+  }
+
+  // repl
+  def main(args: Array[String]) = {
+    val repl_env: Map[Symbol,Any] = Map(
+      '+ -> ((a: List[Any]) => a(0).asInstanceOf[Long] + a(1).asInstanceOf[Long]),
+      '- -> ((a: List[Any]) => a(0).asInstanceOf[Long] - a(1).asInstanceOf[Long]),
+      '* -> ((a: List[Any]) => a(0).asInstanceOf[Long] * a(1).asInstanceOf[Long]),
+      '/ -> ((a: List[Any]) => a(0).asInstanceOf[Long] / a(1).asInstanceOf[Long]))
+    val REP = (str: String) => {
+      PRINT(EVAL(READ(str), repl_env))
+    }
+
+    var line:String = null
+    while ({line = readLine("user> "); line != null}) {
+      try {
+        println(REP(line))
+      } catch {
+        case e : Exception => {
+          println("Error: " + e.getMessage)
+          println("    " + e.getStackTrace.mkString("\n    "))
+        }
+      }
+    }
+  }
+}
+
+// vim: ts=2:sw=2