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|
use crate::r#type::Type;
impl Type {
/// Checks if this type is known as the given other type,
/// ie. checks if there exists an implicit conversion from
/// one to the other.
///
/// Currently this is only needed for list to vec conversions.
/// ```rust
/// use myslip::r#type::{Type::*, util::*};
/// assert!(List(vec![Integer, Integer, Integer]).aka(&vecof(Integer)));
/// ```
///
/// Preferrably this should also work with generics:
/// ```rust
/// use myslip::r#type::{Type::*, util::*};
/// assert!(List(vec![Integer, Boolean, Integer]).aka(&vecof(vt("T"))));
/// assert!(List(vec![Integer, Boolean, vt("X")]).aka(&vecof(vt("T"))));
/// ```
///
/// But of course it also should know when to fail:
/// ```rust
/// use myslip::r#type::{Type::*, util::*};
/// assert!(!List(vec![Integer, Boolean]).aka(&vecof(Integer)));
/// assert!(!List(vec![Integer, Boolean]).aka(&vecof(Boolean)));
/// ```
pub fn aka(&self, known_as: &Type) -> bool {
todo!()
}
fn least_general_supertype(&self, other: &Type) -> Type {
todo!()
}
}
#[cfg(test)]
mod tests {
use crate::r#type::{Type::*, util::*};
#[test]
fn test_basic_general_supertypes() {
assert_eq!(Integer.least_general_supertype(&Integer), Integer);
assert_eq!(Integer.least_general_supertype(&Boolean), vt("T"));
}
#[test]
fn test_compound_general_supertypes() {
assert_eq!(
List(vec![Integer, Integer])
.least_general_supertype(
&List(vec![Integer, Integer])
),
List(vec![Integer, Integer])
);
assert_eq!(
List(vec![Integer, Boolean])
.least_general_supertype(
&List(vec![Integer, Integer])
),
List(vec![Integer, vt("T")])
);
assert_eq!(
vecof(Integer)
.least_general_supertype(
&vecof(Integer)
),
vecof(Integer)
);
assert_eq!(
vecof(Integer)
.least_general_supertype(
&vecof(Boolean)
),
vecof(vt("T"))
);
assert_eq!(
List(vec![Integer, Boolean]).least_general_supertype(
&List(vec![Boolean, Integer])
),
List(vec![vt("T"), vt("T")])
);
}
#[test]
fn test_conversion_in_general_supertypes() {
assert_eq!(
List(vec![Integer, Integer]).least_general_supertype(
&vecof(Integer)
),
vecof(Integer)
);
assert_eq!(
List(vec![Integer, Integer]).least_general_supertype(
&List(vec![Integer, Integer, Integer])
),
vecof(Integer)
);
assert_eq!(
List(vec![Integer, Boolean]).least_general_supertype(
&List(vec![Integer, Boolean, Integer])
),
vecof(vt("T"))
);
assert_eq!(
List(vec![Boolean, Integer]).least_general_supertype(
&vecof(Integer)
),
vecof(vt("T"))
);
}
}
|
