alet dependency inference

the `alet` macro seems to require that variables are referenced in the top-level of binding forms in order to infer dependencies

thus when i am calling some functions created with `defnk` i have to add artificial `do` blocks and explicitly refer to dependent variables like this https://www.refheap.com/88d7eba3d8eb9c73e2834f4d4

this seems like a reasonable limitation for the macro - but should be documented