crystal: implement mal in Mal module

crystal/readline.cr

@@ -8,15 +8,18 @@ lib LibReadline
   fun add_history(line : UInt8*)
 end
 
-def my_readline(prompt = "")
-  line = LibReadline.readline(prompt)
-  if line
-    LibReadline.add_history(line)
-    String.new(line)
-  else
-    nil
-  end
-ensure
-  LibC.free(line as Void*) if line
-end
+module Mal
 
+  def my_readline(prompt = "")
+    line = LibReadline.readline(prompt)
+    if line
+      LibReadline.add_history(line)
+      String.new(line)
+    else
+      nil
+    end
+  ensure
+    LibC.free(line as Void*) if line
+  end
+
+end

crystal/step0_repl.cr

@@ -21,6 +21,6 @@ def rep(x)
     read(eval(print(x)))
 end
 
-while line = my_readline("user> ")
+while line = Mal::my_readline("user> ")
     puts rep(line)
 end