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#![deny(clippy::pedantic)]
#![deny(clippy::all)]
//! Tests if multiple generic parameters work, for the case that lifetimes are independent of mapping functions.
//! For simplicity, it just creates a `FreeResult` based on `Result`.
use higher::{Apply, Bind, Functor};
use higher_free_macro::free;
free!(FreeResult<O,E>, Result<FreeResult<O,E>,E>);
//just to appease clippy without disabling the lint....
macro_rules! assert_nearly_equal {
($a:expr, $b:expr, $c:expr) => {
assert!((($a) - ($b)).abs() < $c)
};
}
#[test]
fn test_multiple_generics() {
let m: FreeResult<_, String> = FreeResult::lift_f(Ok(37u32));
let m = m.fmap(|x| x * 2);
let m = m.bind(|x| FreeResult::Free(Box::new(Ok(FreeResult::Pure(x)))));
let f = FreeResult::Pure((|x| x * 3).into());
let m = m.apply(f);
match m {
FreeResult::Free(b) => match *b {
Ok(FreeResult::Free(b)) => match *b {
Ok(FreeResult::Pure(x)) => assert_eq!(x, 37 * 6),
_ => unreachable!(),
},
_ => unreachable!(),
},
FreeResult::Pure(_) => unreachable!(),
}
}
#[test]
fn test_multiple_generics2() {
let m: FreeResult<_, String> = FreeResult::lift_f(Ok(37u32));
let m = m.bind(|_| FreeResult::<u32, _>::lift_f(Err("An early out.".to_owned())));
match m {
FreeResult::Free(m) => match &*m {
Ok(FreeResult::Free(m)) => match &**m {
Err(e) => assert_eq!(e, "An early out."),
_ => unreachable!(),
},
_ => unreachable!(),
},
FreeResult::Pure(_) => unreachable!(),
}
}
#[test]
fn test_multiple_generics3() {
let m: FreeResult<_, String> = FreeResult::lift_f(Ok(37u32));
let f: FreeResult<_, String> =
FreeResult::Pure(|x: u32| -> f64 { f64::from(x) * 0.5f64 }).fmap(Into::into);
let m = m.apply(f);
match m {
FreeResult::Free(m) => match &*m {
Ok(k) => match k {
FreeResult::Pure(k) => assert_nearly_equal!(18.5f64, *k, f64::EPSILON),
FreeResult::Free(_) => unreachable!(),
},
Err(_) => unreachable!(),
},
FreeResult::Pure(_) => unreachable!(),
}
}
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