TypeScript: Create an "Uncapitalize" Type

Imagine you're working with string literals in TypeScript and need to dynamically transform them. A common requirement is to convert the first letter of a string literal to lowercase while leaving the rest of the string unchanged. This "Uncapitalize" type is incredibly useful for standardizing string keys, property names, or display text within your TypeScript applications.

Problem Description

Your task is to create a generic TypeScript type named Uncapitalize that accepts a single type argument, S. This type should return a new string literal type where the first character of S is converted to its lowercase equivalent, and all subsequent characters remain as they were.

Key Requirements:

• The Uncapitalize type should work with string literal types.
• It must correctly handle cases where the input string starts with an uppercase letter.
• It must correctly handle cases where the input string already starts with a lowercase letter.
• It must correctly handle cases where the input string is empty.
• It must correctly handle cases where the input string starts with a non-alphabetic character.

Expected Behavior:

• If S is "Hello", Uncapitalize<S> should be "hello".
• If S is "world", Uncapitalize<S> should be "world".
• If S is "123", Uncapitalize<S> should be "123".
• If S is "", Uncapitalize<S> should be "".

Examples

Example 1:

Input: Uncapitalize<"FirstName">
Output: "firstName"
Explanation: The first character 'F' is converted to 'f'. The rest of the string "irstName" remains unchanged.

Example 2:

Input: Uncapitalize<"lastName">
Output: "lastName"
Explanation: The first character 'l' is already lowercase, so the string remains unchanged.

Example 3:

Input: Uncapitalize<"">
Output: ""
Explanation: An empty string input results in an empty string output.

Example 4:

Input: Uncapitalize<"1st Place">
Output: "1st Place"
Explanation: The first character '1' is not an uppercase letter, so the string remains unchanged.

Constraints

• The input type S must be a string literal type or ''.
• The solution should be purely type-level, without any runtime JavaScript code.
• Focus on correctness and clarity of the type definition. Performance is not a primary concern for this type-level operation.

Notes

This problem leverages TypeScript's template literal types and conditional types. You'll likely need to break down the input string S into its first character and the rest of the string. Consider how you can conditionally transform the first character based on whether it's an uppercase letter.

Think about how to access individual characters within a string literal type and how to construct a new string literal type from parts. You might find the built-in utility types useful, or you might need to construct your own conditional logic. Good luck!