Gain insights into functional programming with OCaml and Haskell, explore lambda calculus, abstractions, and dataflows, and learn to apply these concepts to real-world scenarios, contrasting with Java.

ocaml_utop_haskell.tar.gz

OCaml

Functional programming is a paradigm that builds complete applications by breaking down programs into constituent functions that empowers developers to build fast, bug-resistant applications.

You’ll be introduced to functional programming with illustrative examples contrasting the more widely used imperative programming paradigm. You’ll review lambda calculus as an introduction to expressions, the building blocks of functional programs. You’ll continue with abstractions and complex data types before exploring common computation patterns. Next, you’ll learn how dataflows create whole programs out of existing functions. Finally, you’ll finish by applying your functional programming knowledge to various real-world scenarios. At each step, you’ll learn OCaml and Haskell, while contrasting imperative programming with Java.

By the end of this course, you’ll be prepared to use functional programming in your daily work and have the framework to know when to use either imperative or functional paradigms.

Mastering Functional Programming with OCaml and Haskell

# Challenge 1: Find the longest string in a string list

Write an OCaml function, `longest_string: string list -> string option`, to find the longest string in a list of strings.

Examples:

```ocaml
longest_string [] = None
longest_string ["a"; "ABC"; "ab"] = Some "abc"
```

Hint: You can use OCaml's `String.length` function to compute the length of a string.

(** [longest_string n] is the longest string in the string list [l]. *)
let rec longest_string l = None (* TODO: Replace the hard-coded value with your code here *)

let list_to_string l = "[" ^ String.concat "," l ^ "]"

let option_to_string o = match o with
                                 | None -> "None"
                                 | Some x -> "Some " ^ x

let rec longest_string l =
          match l with
          | [] -> None
          | hd :: tl -> let s = longest_string tl in
                           match s with
                           | None -> Some hd
                           | Some x -> if String.length hd > String.length x then Some hd else Some x




# Challenge 2: Concatenate strings

Write an OCaml function, `concat: string -> string list -> string`, to add a string `s` and a list of string `l`, and then concatenate all the strings in the list delimited by `s`.

Examples:

```ocaml
concat "," [] = ""
concat "," ["a"] = "a"
concat "," ["a"; "b"] = "a,b"
concat "--" ["a"; "b"; "c"] = "a--b--c"
```


Hint: You can use OCaml's function `String.length` to compute the length of a string.

Let's solve coding challenges to practice compound datatypes.

Introduction

Expressions: Building Blocks of Functional Programs

Building Abstractions with Functions

Compound Data Types

Common Computation Patterns

Dataflow Programming with Functions

Applying Functional Programming to Various Domains

Conclusion

Appendix

Programming Challenges

Challenge 1: Find the longest string in a string list

Challenge 2: Concatenate strings