TypeScript Type of generic function
The last line declares a variable named myIdentity. The variable is of a function type, a generic function (the <T> makes the it the signature of a generic function, more type arguments could be in the list) which takes an argument of type T and returns a value of typeT. And then initializes the variable with the identity function which conforms to the declared signature of myIdentity.
You may want to do this in order to assign different functions to myIdentity based on runtime conditions. Or declare a parameter of this type and pass it to a function that can invoke it later.
Lets say that from the compiler perspective explicit type declaration is not necessarybecause of type inference.
let myIdentity: <T>(arg: T) => T = identity;is equivalent to
let myIdentity = identityNevertheless, from the human side, it can be used for improving code readability.