diff --git a/v0/src/buffer.c b/v0/buffer.c
similarity index 100%
rename from v0/src/buffer.c
rename to v0/buffer.c
diff --git a/v0/buffer.h b/v0/buffer.h
new file mode 100644
index 0000000..9b5c8e3
--- /dev/null
+++ b/v0/buffer.h
@@ -0,0 +1,50 @@
+/**
+ * An interface that wraps files and strings.
+ * Allows stream–like reading from it.
+ */
+#ifndef BUFFER_H
+#define BUFFER_H
+
+/**
+ * An interface to a source of textual data.
+ */
+typedef struct Buffer Buffer;
+
+/**
+ * Opens a file.
+ * 
+ * @param path The path to the file.
+ * @returns The newly–opened buffer.
+ */
+Buffer* buffer_open_file(const char* path);
+
+/**
+ * Opens a string.
+ * 
+ * The string is not copied, and must not be free'd until the
+ * buffer itself has been closed.
+ * 
+ * @param string The contents stored in the buffer.
+ * @returns A newly–opened buffer that reads from the string.
+ */
+Buffer* buffer_open_string(const char* string);
+
+/**
+ * Closes the buffer.
+ * 
+ * @param buffer The buffer to close.
+ */
+void buffer_close(Buffer* buffer);
+
+/**
+ * Reads a single character from the buffer.
+ * 
+ * If there are no more characters in the buffer,
+ * this returns `-1`.
+ * 
+ * @param buffer The buffer to read from.
+ * @returns the next character in the buffer.
+ */
+char buffer_read(Buffer* buffer);
+
+#endif
diff --git a/v0/main.c b/v0/main.c
new file mode 100644
index 0000000..932a6c7
--- /dev/null
+++ b/v0/main.c
@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+int main(int argc, char** argv) {
+	puts("Hello, world");
+}
\ No newline at end of file
diff --git a/v0/tests/test.c b/v0/test.c
similarity index 100%
rename from v0/tests/test.c
rename to v0/test.c
diff --git a/v0/tests/test.h b/v0/test.h
similarity index 100%
rename from v0/tests/test.h
rename to v0/test.h
diff --git a/v0/tests/test_buffer.c b/v0/test_buffer.c
similarity index 89%
rename from v0/tests/test_buffer.c
rename to v0/test_buffer.c
index 9644be5..69fa7d2 100644
--- a/v0/tests/test_buffer.c
+++ b/v0/test_buffer.c
@@ -1,5 +1,5 @@
 #include "test.h"
-#include "../src/buffer.h"
+#include "buffer.h"
 #include <stdio.h>
 
 // @copilot add test for reading from a file.
@@ -27,7 +27,7 @@ static void test_buffer_string_eof_after_content(void) {
 }
 
 static void test_buffer_file_reads_chars(void) {
-    Buffer* buf = buffer_open_file("v0/tests/test_buffer.txt");
+    Buffer* buf = buffer_open_file("v0/test_buffer.txt");
     if (buf == NULL) fail("could not open file");
     if (buffer_read(buf) != 'a') fail("expected 'a'");
     if (buffer_read(buf) != 'b') fail("expected 'b'");
@@ -38,6 +38,6 @@ static void test_buffer_file_reads_chars(void) {
 }
 
 static void test_buffer_file_open_fail(void) {
-    Buffer* buf = buffer_open_file("v0/tests/does_not_exist.txt");
+    Buffer* buf = buffer_open_file("v0/does_not_exist.txt");
     if (buf != NULL) fail("expected NULL for non-existent file");
 }
diff --git a/v0/tests/test_buffer.txt b/v0/test_buffer.txt
similarity index 100%
rename from v0/tests/test_buffer.txt
rename to v0/test_buffer.txt
diff --git a/v0/token.h b/v0/token.h
new file mode 100644
index 0000000..e4a5002
--- /dev/null
+++ b/v0/token.h
@@ -0,0 +1,49 @@
+/**
+ * Contains the interface for reading tokens from a file.
+ */
+#ifndef TOKEN_H
+#define TOKEN_H
+
+typedef enum {
+	// Keywords
+	TOKEN_MODULE,
+	TOKEN_IMPORT,
+	TOKEN_SEMICOLON,
+
+	// Symbols
+	TOKEN_PARENT_OPEN,
+	TOKEN_PARENT_CLOSE,
+	TOKEN_BRACKET_OPEN,
+	TOKEN_BRACKET_CLOSE,
+	TOKEN_COMMA,
+
+	// Primitives
+	TOKEN_VOID,
+
+	// Variable
+	TOKEN_IDENTIFIER,
+} Token;
+
+typedef struct TokenStream TokenStream;
+
+/**
+ * Opens a file and returns a TokenStream for it.
+ * @param path The path to the file.
+ * @returns A handle to the TokenStream.
+ */
+TokenStream* tokenstream_open(const char* path);
+
+/**
+ * Closes a TokenStream.
+ * @param ts The TokenStream to close.
+ */
+void tokenstream_close(TokenStream* ts);
+
+/**
+ * Gets the next token from the TokenStream.
+ * @param ts The TokenStream to read from.
+ * @returns The next token read.
+ */
+Token tokenstream_next(TokenStream* ts);
+
+#endif
\ No newline at end of file