Created
May 17, 2019 11:01
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| use frunk::{ | |
| hlist::{HCons, HNil}, | |
| labelled::{Field, LabelledGeneric}, | |
| }; | |
| use frunk_derives::LabelledGeneric; | |
| trait GShow<T> { | |
| fn gshow(self) -> String; | |
| } | |
| trait Show<T> { | |
| fn show(self) -> String; | |
| } | |
| #[derive(LabelledGeneric)] | |
| struct A { | |
| a: String, | |
| b: i32, | |
| } | |
| fn main() { | |
| println!( | |
| "{}", | |
| A { | |
| a: "hello".into(), | |
| b: 32 | |
| } | |
| .show() | |
| ); | |
| } | |
| impl<N, T, Tail, A, B> GShow<HCons<A, B>> for HCons<Field<N, T>, Tail> | |
| where | |
| Tail: GShow<B>, | |
| T: Show<A>, | |
| { | |
| fn gshow(self) -> String { | |
| let (field, tail) = self.pop(); | |
| format!("{}: {}, {}", field.name, field.value.show(), tail.gshow()) | |
| } | |
| } | |
| impl GShow<HNil> for HNil { | |
| fn gshow(self) -> String { | |
| String::new() | |
| } | |
| } | |
| impl Show<HNil> for String { | |
| fn show(self) -> String { | |
| self | |
| } | |
| } | |
| impl Show<HNil> for i32 { | |
| fn show(self) -> String { | |
| self.to_string() | |
| } | |
| } | |
| impl<T, A, B> Show<HCons<A, B>> for T | |
| where | |
| T: LabelledGeneric, | |
| T::Repr: GShow<HCons<A, B>>, | |
| { | |
| fn show(self) -> String { | |
| LabelledGeneric::into(self).gshow() | |
| } | |
| } |
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