feat: implement file writer

include/compiler/fzl_writer.h

@@ -0,0 +1,25 @@
+#ifndef FZL_WRITER_H
+#define FZL_WRITER_H
+
+#include <compiler/fzl_walker.h>
+#include <compiler/utils/fzl_const_pool.h>
+
+// File writer descriptor
+typedef struct
+{
+  const char *filepath;
+} fzl_writer_t;
+
+// Allocate writer
+fzl_writer_t *fzl_mkwriter(const char *filepath);
+
+// Write out a file
+int fzl_write(fzl_writer_t *writer, fzl_walker_t *walker);
+
+// Get last writer error message
+char *fzl_writer_geterror();
+
+// Free writer
+void fzl_freewriter(fzl_writer_t *writer);
+
+#endif // FZL_WRITER_H