Checkpoint

src/repl/Repl.kt

@@ -6,14 +6,15 @@ import io.Terminal
 import parser.ReplParser
 import prolog.Answer
 import prolog.Answers
+import prolog.Program
 
 class Repl {
     private val io = Terminal()
     private val parser = ReplParser()
     private val preprocessor = Preprocessor()
 
-    fun start() {
-        io.say("Prolog REPL. Type '^D' to quit.\n")
+    init {
+        welcome()
         while (true) {
             try {
                 printAnswers(query())
@@ -23,15 +24,19 @@ class Repl {
         }
     }
 
-    fun query(): Answers {
+    private fun welcome() {
+        io.checkNewLine()
+        io.say("Prolog REPL. Type '^D' to quit.\n")
+    }
+
+    private fun query(): Answers {
         val queryString = io.prompt("?-", { "|  " })
         val simpleQuery = parser.parse(queryString)
         val query = preprocessor.preprocess(simpleQuery)
-        Logger.debug("Satisfying query: $query")
         return query.satisfy(emptyMap())
     }
 
-    fun printAnswers(answers: Answers) {
+    private fun printAnswers(answers: Answers) {
         val knownCommands = setOf(";", "a", ".", "h")
 
         val iterator = answers.iterator()
@@ -68,7 +73,7 @@ class Repl {
         io.say("\n")
     }
 
-    fun help(): String {
+    private fun help(): String {
         io.say("Commands:\n")
         io.say("  ;   find next solution\n")
         io.say("  a   abort\n")
@@ -77,12 +82,13 @@ class Repl {
         return ""
     }
 
-    fun prettyPrint(result: Answer): String {
+    private fun prettyPrint(result: Answer): String {
         result.fold(
             onSuccess = {
                 val subs = result.getOrNull()!!
                 if (subs.isEmpty()) {
-                    return "true."
+                    io.checkNewLine()
+                    return "true.\n"
                 }
                 return subs.entries.joinToString(",\n") { "${it.key} = ${it.value}" }
             },