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Question-1. What is ReScript?
Answer-1: ReScript is a strongly typed, JavaScript-like language designed for building web applications efficiently.
Question-2. What was ReScript previously known as?
Answer-2: ReScript was formerly known as BuckleScript and was related to ReasonML.
Question-3. How does ReScript compare to JavaScript?
Answer-3: ReScript is statically typed, compiles to highly optimized JavaScript, and eliminates runtime type errors.
Question-4. What is the file extension for ReScript?
Answer-4: ReScript source files use the .res extension.
Question-5. How do you declare a variable in ReScript?
Answer-5: Use let, e.g., let x = 10;.
Question-6. Does ReScript support mutability?
Answer-6: By default, ReScript variables are immutable; for mutability, use ref.
Question-7. How do you define a function in ReScript?
Answer-7: Use let, e.g., let add = (a, b) => a + b;.
Question-8. How do you enforce types in ReScript?
Answer-8: ReScript has a strong type system that infers types automatically but allows explicit annotations.
Question-9. How do you define a type alias in ReScript?
Answer-9: Use type, e.g., type age = int;.
Question-10. How do you define a tuple in ReScript?
Answer-10: Use (value1, value2), e.g., let person = ("Alice", 25);.
Question-11. How do you access tuple elements?
Answer-11: Use pattern matching, e.g., let (name, age) = person;.
Question-12. What is pattern matching in ReScript?
Answer-12: Pattern matching is used to destructure and match values, e.g., `switch x {
Question-13. How do you define a list in ReScript?
Answer-13: Use [value1, value2], e.g., let numbers = [1, 2, 3];.
Question-14. How do you add an element to a list?
Answer-14: Use ::, e.g., let newList = 0 :: numbers;.
Question-15. How do you create an object in ReScript?
Answer-15: Use { key: value }, e.g., let user = { name: "Alice", age: 25 };.
Question-16. How do you access object properties in ReScript?
Answer-16: Use dot notation, e.g., user.name;.
Question-17. How do you define a record in ReScript?
Answer-17: Use type, e.g., type person = { name: string, age: int };.
Question-18. How do you create an instance of a record?
Answer-18: Use {}, e.g., let p: person = { name: "Alice", age: 25 };.
Question-19. How do you define a union type in ReScript?
Answer-19: Use `
Question-20. How do you handle a union type in ReScript?
Answer-20: Use switch, e.g., `switch shape {
Question-21. What is the @genType annotation?
Answer-21: It generates TypeScript or Flow bindings from ReScript.
Question-22. How do you interact with JavaScript in ReScript?
Answer-22: Use @bs.val for values and @bs.module for modules.
Question-23. How do you define an external JavaScript function in ReScript?
Answer-23: Use @bs.val, e.g., @bs.val external log: string => unit = "console.log";.
Question-24. How do you call a JavaScript function from ReScript?
Answer-24: Use Js.log("Hello"); after defining it as an external binding.
Question-25. How do you import a JavaScript module in ReScript?
Answer-25: Use @bs.module, e.g., @bs.module("fs") external readFile: (string, string) => string = "readFileSync";.
Question-26. How do you handle exceptions in ReScript?
Answer-26: Use try and catch, e.g., try { riskyFunction(); } catch { _ => "Error" };.
Question-27. How do you work with promises in ReScript?
Answer-27: Use Js.Promise.t, e.g., let p: Js.Promise.t
Question-28. How do you handle a resolved promise in ReScript?
Answer-28: Use .then_, e.g., p->Js.Promise.then_(res => { Js.log(res); Js.Promise.resolve(); });.
Question-29. What is pipe (->) in ReScript?
Answer-29: It allows function chaining, e.g., data->process->output;.
Question-30. How do you install ReScript?
Answer-30: Use npm install -g rescript.
Question-31. How do you compile a ReScript project?
Answer-31: Run rescript build.
Question-32. How do you watch for changes while developing in ReScript?
Answer-32: Run rescript build -w.
Question-33. How do you create a ReScript React component?
Answer-33: Use [@react.component] let make = () =>
Question-34. How do you handle props in a ReScript React component?
Answer-34: Define parameters, e.g., [@react.component] let make = (~name) =>
Question-35. How do you define a reducer in ReScript React?
Answer-35: Use React.useReducer, e.g., let (state, dispatch) = React.useReducer(reducer, initialState);.
Question-36. How do you write a type-safe event handler in ReScript?
Answer-36: Use ReactEvent.Mouse.t, e.g., let handleClick = (event: ReactEvent.Mouse.t) => Js.log("Clicked");.
Question-37. What is the difference between let and let%private in ReScript?
Answer-37: let defines a public function, while let%private restricts it to the module.
Question-38. How do you import TypeScript/JavaScript types into ReScript?
Answer-38: Use @genType and external bindings.
Question-39. Can ReScript be used without Node.js?
Answer-39: No, it relies on the Node.js ecosystem for tooling.
Question-40. How do you declare an interface in ReScript?
Answer-40: Use objects and records with type definitions.
Question-41. How do you perform string interpolation in ReScript?
Answer-41: Use Js.String.concat, e.g., "Hello " ++ name;.
Question-42. What are ReScript?s main advantages over TypeScript?
Answer-42: Better type inference, faster compilation, and stronger safety guarantees.
Question-43. How do you create an alias for a type in ReScript?
Answer-43: Use type alias = existingType;.
Question-44. How do you check if an option value is Some or None?
Answer-44: Use switch, e.g., `switch myValue {
Question-45. How do you use the Option type in ReScript?
Answer-45: Use Some(value) or None.
Question-46. What are the built-in modules in ReScript?
Answer-46: Modules like Js, Array, List, and String.
Question-47. How do you use ReScript with GraphQL?
Answer-47: Use the rescript-graphql package.
Question-48. How do you configure the ReScript compiler?
Answer-48: Modify bsconfig.json.
Question-49. What is the purpose of bs-platform?
Answer-49: It provides the ReScript compiler and runtime libraries.
Question-50. Where can you learn more about ReScript?
Answer-50: Visit the official site: https://rescript-lang.org.
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