Alias expression

[Specy]

create syntax for aliases, something like

min $cost
s.t.
    alias $cost = ...

    $cost >= 200

Where the aliases are the first thing scanned and they will be replaced at build time by simply replacing the expression inside of the alias (this might cause issues with the type checker though, the return value of the alias must be the same as the return value of the expression, at that point we can typecheck the aliases before checking the constraints and objective function)

[Specy]

And why not, generics too so you can do things like

alias $double<i> = x_i * 2

$double(i) <= 10 for i in 0..10