As is pretty common with ChatGPT, some parts of this are outright hallucinations:

• there is no strict option to Macro.escape
• Macro.escape does not compile strings into ASTs; if you pass it a string it will return it unchanged
• Code.string_to_quoted (no !) does not return an AST, it returns either {:ok, ast} or an error tuple
• the result of Code.string_to_quoted has not been “compiled”, it has been parsed into an AST ready to be compiled

But some parts are mostly correct. There is a relationship between Code.eval_string and Code.string_to_quoted! + Code.eval_quoted because they both make use of the same underlying compiler machinery.

Code.eval_string has three steps:

• prepare an env with env_for_eval
• convert the supplied string to forms with :elixir.string_to_quoted!
• evaluate the forms by calling :elixir.eval_forms

Code.string_to_quoted! does only the middle step:

while Code.eval_quoted does the first and last steps:

A minor detail: :elixir.eval_quoted does a tiny bit of argument reformatting before calling :elixir.eval_forms

As to your original question, the above analysis should make clear that Code.string_to_quoted! at boot + Code.eval_quoted invoked over and over will be faster than Code.eval_string invoked over and over since it does the string_to_quoted! part once instead of over and over (and otherwise does the same thing).

An even faster alternative would be:

• at boot, parse all the AST once with Code.string_to_quoted!
• at boot, take all those AST fragments and stitch them together into a module definition
• call the functions over and over with apply, at normal speed for compiled code

IMO a bigger question is “what happens when one of these functions is configured with a fatal error, like closing a block with ned?”

• Code.eval_string will crash with an exception when you try to run the function
• Code.string_to_quoted! called at boot-time will crash with an exception and prevent application startup
• Code.string_to_quoted (note no !) will return an error tuple explaining the situation

Your application’s specific needs should help you decide which of these is desirable / acceptable.