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AI solution for TypeScript puzzle on BFE.dev 42. implement Equal<A, B>

Solution:

``````type Equal<A, B> =
(<T>() => T extends A ? true : false) extends
(<T>() => T extends B ? true : false) ? true : false;

// test cases
type Test1 = Equal<any, any>; // true
type Test2 = Equal<any, 1>; // false
type Test3 = Equal<never, never>; // true
type Test4 = Equal<'BFE', 'BFE'>; // true
type Test5 = Equal<'BFE', string>; // false
type Test6 = Equal<1 | 2, 2 | 1>; // true
type Test7 = Equal<{ a: number }, { a: number }>; // true``````

Explanation:

We first define the `Equal` type that takes two types `A` and `B`. We use a conditional type with two functions to check if the two types are identical. The first function `(<T>() => T extends A ? true : false)` checks if any type `T` extends `A`. If it does, then it returns `true`, else it returns `false`. Similarly, the second function `(<T>() => T extends B ? true : false)` checks if any type `T` extends `B`. If it does, then it returns `true`, else it returns `false`. We then use a conditional type to check if the first function extends the second function or vice versa. If it does, then the two types are identical and the `Equal` type returns `true`, else it returns `false`.

Note that the `Equal` type uses a generic function `(<T>() => T extends A ? true : false)` instead of a direct comparison between `A` and `B`. This is because TypeScript does not allow direct comparisons between two types.

Also note that the `Equal` type may not work correctly in some cases, such as when dealing with recursive types or types with circular references. However, for the given test cases, it should work as expected.