I kind of want to see an ORM try something like this.

You can't do this in most languages because of if statements, which cannot be analyzed in that way and break the abstraction. You'd either need macro-based function definitions (Lisp, Elixir), bytecode inspection (like in e.g. Pytorch compile), or maybe built-in laziness (Haskell).

Edit: Or full object orientation like in Smalltalk, where if statements are just calls to .ifTrue and .ifFalse on a true/false object, and hence can be simulated.