start actually writing down stuff for const eval

Author: lcnr

draft-rfcs/const-evaluatable-checked.md

@@ -0,0 +1,12 @@
+# const evaluatable checked
+
+TODO: All of this :)
+
+## Requirements
+
+For this to work, const operations have to be both pure and deterministic, at least when they are used in the type system.
+
+FIXME: const allocations?
+FIXME: non-det floats, are they are problem? We use `ap_float` which is hopefully deterministic.
+FIXME: looking at pointers.
+TODO: let `const-eval` figure this out.