diff --git a/impls/io/step2_eval.io b/impls/io/step2_eval.io
index 1b9e86e455..7f039e06dd 100644
--- a/impls/io/step2_eval.io
+++ b/impls/io/step2_eval.io
@@ -8,7 +8,7 @@ eval_ast := method(ast, env,
 
 EVAL := method(ast, env,
 
-    # "EVAL: " .. PRINT(ast)) println
+   //  "EVAL: " .. PRINT(ast) println
 
    (ast type) switch(
        "MalSymbol", return(env at(ast val) ifNil(Exception raise("'" .. (ast val) "' not found"))),
diff --git a/impls/scala/step2_eval.scala b/impls/scala/step2_eval.scala
index 8d926a9ca1..28fd62f9b6 100644
--- a/impls/scala/step2_eval.scala
+++ b/impls/scala/step2_eval.scala
@@ -1,4 +1,4 @@
-import types.{MalList, _list_Q, MalVector, MalHashMap, MalFunction}
+import types.{MalList, _list_Q, MalVector, MalHashMap, Func}
 
 object step2_eval {
   // read
@@ -7,7 +7,7 @@ object step2_eval {
   }
 
   // eval
-  def eval_ast(ast: Any, env: Map[Symbol,Any]): Any = {
+  def EVAL(ast: Any, env: Map[Symbol,Any]): Any = {
 
     //  println("EVAL: " + printer._pr_str(ast,true))
 
@@ -32,10 +32,10 @@ object step2_eval {
         // function call
           EVAL(first, env) match {
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }
diff --git a/impls/scala/step3_env.scala b/impls/scala/step3_env.scala
index 5815155139..0f4afd1583 100644
--- a/impls/scala/step3_env.scala
+++ b/impls/scala/step3_env.scala
@@ -1,4 +1,4 @@
-import types.{MalList, _list_Q, MalVector, MalHashMap, MalFunction}
+import types.{MalList, _list_Q, MalVector, MalHashMap, Func}
 import env.Env
 
 object step3_env {
@@ -8,10 +8,10 @@ object step3_env {
   }
 
   // eval
-  def eval_ast(ast: Any, env: Env): Any = {
+  def EVAL(ast: Any, env: Env): Any = {
 
-    if (env.find(Symbol("DEBUG-EVAL"))) {
-      dbgeval = env.get(Symbol("DEBUG-EVAL"))
+    if (env.find(Symbol("DEBUG-EVAL")) != null) {
+      val dbgeval = env.get(Symbol("DEBUG-EVAL"))
       if (dbgeval != null && dbgeval != false) {
         println("EVAL: " + printer._pr_str(ast,true))
       }
@@ -48,10 +48,10 @@ object step3_env {
         // function call
           EVAL(first, env) match {
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }
diff --git a/impls/scala/step4_if_fn_do.scala b/impls/scala/step4_if_fn_do.scala
index 4b2a1cfce9..5f3c831c1b 100644
--- a/impls/scala/step4_if_fn_do.scala
+++ b/impls/scala/step4_if_fn_do.scala
@@ -9,10 +9,10 @@ object step4_if_fn_do {
   }
 
   // eval
-  def eval_ast(ast: Any, env: Env): Any = {
+  def EVAL(ast: Any, env: Env): Any = {
 
-    if (env.find(Symbol("DEBUG-EVAL"))) {
-      dbgeval = env.get(Symbol("DEBUG-EVAL"))
+    if (env.find(Symbol("DEBUG-EVAL")) != null) {
+      val dbgeval = env.get(Symbol("DEBUG-EVAL"))
       if (dbgeval != null && dbgeval != false) {
         println("EVAL: " + printer._pr_str(ast,true))
       }
@@ -67,10 +67,10 @@ object step4_if_fn_do {
         // function call
           EVAL(first, env) match {
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }
diff --git a/impls/scala/step5_tco.scala b/impls/scala/step5_tco.scala
index 6385a6d0bd..a09f2f84c6 100644
--- a/impls/scala/step5_tco.scala
+++ b/impls/scala/step5_tco.scala
@@ -13,8 +13,8 @@ object step5_tco {
    var ast = orig_ast; var env = orig_env;
    while (true) {
 
-    if (env.find(Symbol("DEBUG-EVAL"))) {
-      dbgeval = env.get(Symbol("DEBUG-EVAL"))
+    if (env.find(Symbol("DEBUG-EVAL")) != null) {
+      val dbgeval = env.get(Symbol("DEBUG-EVAL"))
       if (dbgeval != null && dbgeval != false) {
         println("EVAL: " + printer._pr_str(ast,true))
       }
@@ -72,15 +72,15 @@ object step5_tco {
         // function call
           EVAL(first, env) match {
               case fn: MalFunction => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 env = fn.gen_env(el) 
                 ast = fn.ast  // continue loop (TCO)
               }
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }
diff --git a/impls/scala/step6_file.scala b/impls/scala/step6_file.scala
index 69219ad861..f8602922f3 100644
--- a/impls/scala/step6_file.scala
+++ b/impls/scala/step6_file.scala
@@ -13,8 +13,8 @@ object step6_file {
    var ast = orig_ast; var env = orig_env;
    while (true) {
 
-    if (env.find(Symbol("DEBUG-EVAL"))) {
-      dbgeval = env.get(Symbol("DEBUG-EVAL"))
+    if (env.find(Symbol("DEBUG-EVAL")) != null) {
+      val dbgeval = env.get(Symbol("DEBUG-EVAL"))
       if (dbgeval != null && dbgeval != false) {
         println("EVAL: " + printer._pr_str(ast,true))
       }
@@ -72,15 +72,15 @@ object step6_file {
         // function call
           EVAL(first, env) match {
               case fn: MalFunction => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 env = fn.gen_env(el) 
                 ast = fn.ast  // continue loop (TCO)
               }
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }
diff --git a/impls/scala/step7_quote.scala b/impls/scala/step7_quote.scala
index 0eb77e732d..b25e564de4 100644
--- a/impls/scala/step7_quote.scala
+++ b/impls/scala/step7_quote.scala
@@ -50,8 +50,8 @@ object step7_quote {
    var ast = orig_ast; var env = orig_env;
    while (true) {
 
-    if (env.find(Symbol("DEBUG-EVAL"))) {
-      dbgeval = env.get(Symbol("DEBUG-EVAL"))
+    if (env.find(Symbol("DEBUG-EVAL")) != null) {
+      val dbgeval = env.get(Symbol("DEBUG-EVAL"))
       if (dbgeval != null && dbgeval != false) {
         println("EVAL: " + printer._pr_str(ast,true))
       }
@@ -115,15 +115,15 @@ object step7_quote {
         // function call
           EVAL(first, env) match {
               case fn: MalFunction => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 env = fn.gen_env(el) 
                 ast = fn.ast  // continue loop (TCO)
               }
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }
diff --git a/impls/scala/step8_macros.scala b/impls/scala/step8_macros.scala
index 924eabe651..a980a55e09 100644
--- a/impls/scala/step8_macros.scala
+++ b/impls/scala/step8_macros.scala
@@ -50,8 +50,8 @@ object step8_macros {
    var ast = orig_ast; var env = orig_env;
    while (true) {
 
-    if (env.find(Symbol("DEBUG-EVAL"))) {
-      dbgeval = env.get(Symbol("DEBUG-EVAL"))
+    if (env.find(Symbol("DEBUG-EVAL")) != null) {
+      val dbgeval = env.get(Symbol("DEBUG-EVAL"))
       if (dbgeval != null && dbgeval != false) {
         println("EVAL: " + printer._pr_str(ast,true))
       }
@@ -123,16 +123,16 @@ object step8_macros {
                if (fn.ismacro) {
                 ast = fn(rest)  // continue loop (TCO)
                } else {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 env = fn.gen_env(el) 
                 ast = fn.ast  // continue loop (TCO)
                }
               }
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }
diff --git a/impls/scala/step9_try.scala b/impls/scala/step9_try.scala
index 6fed3444cf..fe4c70168c 100644
--- a/impls/scala/step9_try.scala
+++ b/impls/scala/step9_try.scala
@@ -50,8 +50,8 @@ object step9_try {
    var ast = orig_ast; var env = orig_env;
    while (true) {
 
-    if (env.find(Symbol("DEBUG-EVAL"))) {
-      dbgeval = env.get(Symbol("DEBUG-EVAL"))
+    if (env.find(Symbol("DEBUG-EVAL")) != null) {
+      val dbgeval = env.get(Symbol("DEBUG-EVAL"))
       if (dbgeval != null && dbgeval != false) {
         println("EVAL: " + printer._pr_str(ast,true))
       }
@@ -144,16 +144,16 @@ object step9_try {
                if (fn.ismacro) {
                 ast = fn(rest)  // continue loop (TCO)
                } else {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 env = fn.gen_env(el) 
                 ast = fn.ast  // continue loop (TCO)
                }
               }
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }
diff --git a/impls/scala/stepA_mal.scala b/impls/scala/stepA_mal.scala
index 5d6a2cdc22..e54a95fb5e 100644
--- a/impls/scala/stepA_mal.scala
+++ b/impls/scala/stepA_mal.scala
@@ -50,8 +50,8 @@ object stepA_mal {
    var ast = orig_ast; var env = orig_env;
    while (true) {
 
-    if (env.find(Symbol("DEBUG-EVAL"))) {
-      dbgeval = env.get(Symbol("DEBUG-EVAL"))
+    if (env.find(Symbol("DEBUG-EVAL")) != null) {
+      val dbgeval = env.get(Symbol("DEBUG-EVAL"))
       if (dbgeval != null && dbgeval != false) {
         println("EVAL: " + printer._pr_str(ast,true))
       }
@@ -144,16 +144,16 @@ object stepA_mal {
                if (fn.ismacro) {
                 ast = fn(rest)  // continue loop (TCO)
                } else {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 env = fn.gen_env(el) 
                 ast = fn.ast  // continue loop (TCO)
                }
               }
               case fn: Func => {
-                el = rest.map(EVAL(_, env))
+                val el = rest.map(EVAL(_, env))
                 return fn(el)
               }
-              case _ => {
+              case f => {
                 throw new Exception("attempt to call non-function: " + f)
               }
           }