Functional programming and object-oriented programming are two major programming paradigms, each with its own strengths and weaknesses. Here are some key points to consider when choosing between functional and object-oriented programming:

### When to Choose Functional Programming over Object-Oriented:
1. **Immutability and Pure Functions**: Functional programming promotes immutability and pure functions, which can lead to more predictable and easier-to-reason-about code. If your application requirements benefit from these characteristics, functional programming might be a good choice.

2. **Concurrency and Parallelism**: Functional programming languages often provide features that make it easier to reason about concurrent and parallel code, such as avoiding shared mutable state. If you need to tackle complex concurrency challenges, functional programming can be advantageous.

3. **Data Transformation**: Functional programming is well-suited for tasks involving heavy data transformation or processing, as functions can be composed and combined easily. If your problem involves processing large amounts of data, functional programming can be a better fit.

### Problem Definitions Suited for Functional Programming:
1. **Mathematical Operations**: Functional programming is particularly strong in domains involving mathematical operations, as it allows for easy manipulation of functions and data.

2. **Stateless Transformations**: Tasks that involve stateless transformations, such as parsing data, filtering lists, or mapping over collections, can be effectively handled with functional programming techniques.

3. **Event-Driven Systems**: Functional programming can be beneficial for developing event-driven systems, where functions can be treated as first-class citizens and passed around as arguments or returned as results.

In summary, choosing functional programming over object-oriented programming depends on the nature of the problem you are trying to solve. Functional programming excels in scenarios requiring immutability, pure functions, data transformation, concurrency, and mathematical operations. For specific problem domains like stateless transformations and event-driven systems, functional programming can provide elegant solutions compared to object-oriented programming. It's always beneficial to explore different programming paradigms to expand your programming toolset and enhance your problem-solving skills.