Repl trouble

src/io/IoHandler.kt

@@ -3,7 +3,8 @@ package io
 interface IoHandler {
     fun prompt(
         message: String,
-        hint: () -> String = { "Please enter a valid input." }
+        hint: () -> String = { "Please enter a valid input." },
+        check: (String) -> Boolean = { true }
     ): String
 
     fun say(message: String)

src/io/Terminal.kt

@@ -20,15 +20,16 @@ class Terminal(
 
     override fun prompt(
         message: String,
-        hint: () -> String
+        hint: () -> String,
+        check: (String) -> Boolean,
     ): String {
         say("$message ")
-        var input: String = readLine()
-        while (input.isBlank()) {
+        var input: String = readLine().trim()
+        while (!check(input)) {
             say(hint(), error)
-            input = readLine()
+            input += readLine().trim()
         }
-        return input
+        return input.trim()
     }
 
     override fun say(message: String) {

src/repl/Repl.kt

@@ -29,40 +29,45 @@ class Repl {
     }
 
     private fun query(): Answers {
-        val queryString = io.prompt("?-", { "|  " })
+        val queryString = io.prompt("?-", { "|  " }, { it.endsWith(".") })
         val simpleQuery = parser.parse(queryString)
         val query = preprocessor.preprocess(simpleQuery)
         return query.satisfy(emptyMap())
     }
 
     private fun printAnswers(answers: Answers) {
-        val knownCommands = setOf(";", "a", ".", "h")
-
         val iterator = answers.iterator()
 
         if (!iterator.hasNext()) {
             io.say("false.\n")
-        } else {
-            io.say(prettyPrint(iterator.next()))
+            return
+        }
 
-            while (iterator.hasNext()) {
-                var command = io.prompt("")
+        io.say(prettyPrint(iterator.next()))
 
-                while (command !in knownCommands) {
-                    io.say("Unknown action: $command (h for help)\n")
-                    command = io.prompt("Action?")
+        while (true) {
+            when (io.prompt("")) {
+                ";" -> {
+                    try {
+                        io.say(prettyPrint(iterator.next()))
+                    } catch (_: NoSuchElementException) {
+                        break
+                    }
                 }
 
-                when (command) {
-                    ";" -> {
-                        io.say(prettyPrint(iterator.next()))
-                    }
-                    "a" -> return
-                    "." -> return
-                    "h" -> {
-                        help()
-                        io.say("Action?")
-                    }
+                "a" -> return
+                "." -> {
+                    io.checkNewLine()
+                    return
+                }
+                "h" -> {
+                    help()
+                    io.say("Action?")
+                }
+
+                else -> {
+                    io.say("Unknown action: (h for help)\n")
+                    io.say("Action?")
                 }
             }
         }

tests/prolog/builtins/DatabaseOperatorsTests.kt

@@ -170,11 +170,9 @@ class DatabaseOperatorsTests {
         assertTrue(answer.isSuccess, "Expected success")
         assertTrue(answer.getOrNull()!!.isEmpty(), "Expected no substitutions")
 
-        assertTrue(result.hasNext(), "Expected more results")
         assertEquals(2, predicate.clauses.size, "Expected 2 clauses")
 
         assertTrue(result.next().isSuccess)
-        assertTrue(result.hasNext(), "Expected more results")
         assertTrue(result.next().isSuccess)
 
         assertFalse(result.hasNext(), "Expected more results")
@@ -208,7 +206,6 @@ class DatabaseOperatorsTests {
         assertTrue(subs.isNotEmpty(), "Expected substitutions")
         assertTrue(Variable("X") in subs, "Expected variable X")
         assertEquals(Atom("b"), subs[Variable("X")], "Expected b")
-        assertTrue(result.hasNext(), "Expected more results")
         assertEquals(2, predicate.clauses.size, "Expected 2 clauses")
 
         answer = result.next()
@@ -218,7 +215,6 @@ class DatabaseOperatorsTests {
         assertTrue(subs.isNotEmpty(), "Expected substitutions")
         assertTrue(Variable("X") in subs, "Expected variable X")
         assertEquals(Atom("c"), subs[Variable("X")], "Expected c")
-        assertTrue(result.hasNext(), "Expected more results")
         assertEquals(1, predicate.clauses.size, "Expected 1 clause")
 
         answer = result.next()
@@ -228,8 +224,9 @@ class DatabaseOperatorsTests {
         assertTrue(subs.isNotEmpty(), "Expected substitutions")
         assertTrue(Variable("X") in subs, "Expected variable X")
         assertEquals(Atom("d"), subs[Variable("X")], "Expected d")
-        assertFalse(result.hasNext(), "Expected no more results")
         assertEquals(0, predicate.clauses.size, "Expected no clauses")
+
+        assertFalse(result.hasNext(), "Expected no more results")
     }
 
     @Test