Some improvement, but two unit tests fail.

src/repl.h

@@ -0,0 +1,37 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+
+/* 
+ * File:   repl.h
+ * Author: simon
+ *
+ * Created on 14 August 2017, 14:40
+ */
+
+#ifndef REPL_H
+#define REPL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * The read/eval/print loop
+ * @param in_stream the stream to read from;
+ * @param out_stream the stream to write to;
+ * @param err_stream the stream to send errors to;
+ * @param show_prompt true if prompts should be shown.
+ */
+void repl( FILE* in_stream, FILE* out_stream, FILE* error_stream, 
+          bool show_prompt);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* REPL_H */
+