Is it possible to create make_adapter here? playground link
The basic idea is simple - I’m binding an argument, so I can then create multiple partial applications by calling the result of make_adapter. But I can't figure out how to specify the types.

fn make_adapter<F1, F2>(b: i32) -> impl Fn(F2) -> F1
    where F1: Fn(i32) -> (), F2: Fn(i32, i32) -> ()
{
    let adapt = |f2: F2| -> F1 {
        let f1 = move |a: i32| {
            f2(a, b);
        };
        f1
    };
    adapt
}

fn main() {
    let a: i32 = 123;
    let adapt = make_adapter(456);
    let f1: Box<dyn Fn(i32) -> ()> = Box::new(
        adapt(|a,b| println!("called: {}, {}", a, b))
    );
    f1(a);
}

Errors:

error[E0308]: mismatched types
 --> src/main.rs:9:9
  |
2 | fn make_adapter<F1, F2>(b: i32) -> impl Fn(F2) -> F1
  |                 -- expected this type parameter
...
5 |     let adapt = |f2: F2| -> F1 {
  |                             -- expected `F1` because of return type
6 |         let f1 = move |a: i32| {
  |                  ------------- the found closure
...
9 |         f1
  |         ^^ expected type parameter `F1`, found closure
  |
  = note: expected type parameter `F1`
                    found closure `{closure@src/main.rs:6:18: 6:31}`
  = help: every closure has a distinct type and so could not always match the caller-chosen type of parameter `F1`

error[E0283]: type annotations needed
  --> src/main.rs:17:38
   |
16 |     let adapt = make_adapter(456);
   |                 ----------------- type must be known at this point
17 |     let f1: Box<dyn Fn(i32) -> ()> = Box::new(
   |                                      ^^^^^^^^ cannot infer type of the type parameter `T` declared on the struct `Box`
   |

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