feat: also modularizing main

src/main.c

@@ -1,15 +1,29 @@
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
+
+#include "reader.h"
 
 int main() {
+  /*
   size_t buffer_size;
   size_t initial_buffer_size = 64;
   char *input_buffer;
   char *initial_buffer_position;
   unsigned int how_many_characters_to_read;
+  */
+  char *input_line;
 
   while (1) {
+    printf("$ ");
+    input_line = read_a_line(stdin);
+    if (input_line == NULL) {
+      return 0;
+    }
+
+    printf("command: '%s'\n", input_line);
+
+    free(input_line);
+    /*
     buffer_size = initial_buffer_size;
     how_many_characters_to_read = buffer_size + 1;
     input_buffer = malloc(how_many_characters_to_read);
@@ -32,5 +46,6 @@ int main() {
     printf("%s", input_buffer);
 
     free(input_buffer);
+    */
   }
 }