Problem Narrative

You’re building an internal hiring platform for a fintech company that screens JavaScript candidates at scale (hundreds of thousands of submissions per day). To reduce fraud and keep grading deterministic, the platform runs “vanilla JS riddles” inside a locked-down test framework. Each riddle is a tiny assertion like expect(reverse("abc")).toBe("cba").

Your job is to implement the core assertion evaluator that determines whether each riddle passes without executing JavaScript. Instead, you’ll parse and evaluate a limited, safe subset of expressions.

Formal Problem Statement

Implement evaluate_riddles(riddles: list[str]) -> list[bool].

Each riddle string has the form:

expect(<expr>).toBe(<expr>)

Where <expr> is one of:

1. A string literal in double quotes, containing lowercase letters only: "abc"
2. A non-negative integer literal: 0, 12, 300
3. A function call with one argument: reverse(<expr>), len(<expr>), or isPalindrome(<expr>)

Supported functions:

• reverse(s): returns the reversed string
• len(s): returns the length of the string
• isPalindrome(s): returns true if s equals its reverse, else false

Return a boolean per riddle indicating whether the left and right expressions evaluate to the same value (type-sensitive: string vs int vs bool).

Examples

Example 1

• Input: riddles = ["expect(reverse(\"abc\")).toBe(\"cba\")"]
• Output: [true]
• Explanation: reverse("abc") evaluates to "cba", which equals the right-hand string.

Example 2

• Input: riddles = ["expect(len(reverse(\"ab\"))).toBe(2)", "expect(isPalindrome(\"aba\")).toBe(true)"]
• Output: [true, true]
• Explanation: reverse("ab") -> "ba", len("ba") -> 2. Also, "aba" is a palindrome.

Constraints

• 1 <= riddles.length <= 10^4
• Each riddle length <= 200
• String literals contain only [a-z] (no escapes besides the surrounding quotes in the input representation)
• Expressions are well-formed and contain no spaces

Notes / Clarifications

• Only the exact grammar above appears (no arithmetic, no concatenation, no variables).
• true/false appear only as the output of isPalindrome(...) or as literals on the right/left.
• Comparisons are strict: "2" is not equal to 2.