diff --git a/include/state.h b/include/state.h
index 6879cb8..a4ac336 100644
--- a/include/state.h
+++ b/include/state.h
@@ -30,9 +30,13 @@ sm_yield _sm_noop(sm_state*);
 inline sm_yield sm_end() { return (sm_yield)nullptr; }
 inline sm_yield sm_continue() { return (sm_yield)_sm_noop; }
 
-#define SM_VAR_EX(name, init) _sm_var(state, (name), (init)) //TODO: Replace `name' with (__LINE__ % _SM_STACK_SIZE) pseudo-hashmap
-#define SM_VAR(init) _sm_var<__LINE__, decltype(init)>(state, (init))
-#define SM_SLOT(T) _sm_var<__LINE__, T>(state, {})
+/// --- For accessing generator-local variables stored in the `state` structure.
+
+#define SM_VAR_EX(name, init) _sm_var(state, (name), (init)) // Same as `SM_VAR`, except the slot is explicitly named with a runtime integer value. Must be lower than `_SM_STACK_SIZE`. (TODO: Allow wrapping around this max value with a hashtable that adds new pages with the `next' pointer in the `_sm_user_page' struct.)
+#define SM_VAR(init) _sm_var<__LINE__, decltype(init)>(state, (init)) // Return a pointer to a unique variable on the current state machine's stack. Initialising it with `init' if it doesn't already have a set value.
+#define SM_SLOT(T) _sm_var<__LINE__, T>(state, {}) /// Allocate an uninitialised slot for type `T` on the current state machine's stack frame, returning a pointer to the value. If the value has already been allocated, return a pointer to that value saved in the current frame.
+
+/// --- 
 
 #define SM_BEGIN switch(state->current->pc) { case 0:
 #define SM_END } _sm_pop_stack(state); return sm_end()