Can you explain Cairo v0.10 usage functions as expressions?

It means doing things like

let x = foo(y) + z;
let a = foo(bar(b));

etc.

Note that it currently only works for functions that return a felt (not a tuple) with a known ap change, which means no recursive functions, and no if statements (mostly. I think certain if-statements work but I haven't tried it myself)

I'm not sure that second line works. I thought the same, but I'm getting compile time errors thrown on structures like that expecting bar to be a Struct rather than a function

the first definitely works

This answer was originally posted on StarkNet Discord