disc3

Discussion 3: Introduction to OCaml

Introduction

This exercise consists of a few short functions to help you familiarize yourself with OCaml. You can review the content of the discussion in notes.rb, which includes the topics and examples from the discussion video. Also, check out utop-tutorial.md for an introduction to using utop.

Testing & Submitting

To test locally, run dune runtest -f. There is no submission for this assignment, it is just extra practice.

Part 1: Type inference

At the top of disc3.ml, there are a few function definitions. Try determining the types of these functions and check your answers with utop. This portion of the discussion is not tested (and thus not graded), but these kinds of exercises may appear on quizzes and exams!

Part 2: Type definitions

You will have to fill in definitions for the functions tf1, tf2, tf3 such that they have the type that is expected in the .mli. The operation of the function does not matter, as long as they have the correct types.

tf1 a

• Type: string -> int

tf2 a b c

• Type: 'a -> 'b -> 'b -> bool

tf3 a b

• Type: 'a list -> 'a list -> 'a
• Note: For this one, you can assume that the lists a and b are not empty.

Part 3: Functions

concat str1 str2

• Type: string -> string -> string
• Description: Appends str2 to the end of str1.
• Examples:

  concat "" "" = ""
  concat "" "abc" = "abc"
  concat "xyz" "" = "xyz"
  concat "abc" "xyz" = "abcxyz"

add_to_float integer flt

• Type: int -> float -> float
• Description: Adds integer and flt and returns a float representation of the sum.
• Examples:

  add_to_float 3 4.8 = 7.8
  add_to_float 0 0.0 = 0.0

fib n

• Type: int -> int
• Description: Calculates the nth Fibonacci number.
• Examples:

  fib 0 = 0
  fib 1 = 1
  fib 2 = 1
  fib 3 = 2
  fib 6 = 8

Part 4: Lists

add_three lst

• Type: int list -> int list
• Description: Adds 3 to each element in lst.
• Examples:

  add_three [] = []
  add_three [1] = [4]
  add_three [1; 3; 5] = [4; 6; 8]

filter n lst

• Type: int -> int list -> int list
• Description: Given an integer n and a list lst, Remove elements from lst that are less than n.
• Examples:

  filter 3 [1; 2; 3; 3; 2; 1] = [1; 2; 2; 1]
  filter 5 [-1; 2; 3; 4] = [-1; 2; 3; 4]

double lst

• Type: 'a list -> 'a list
• Description: Given a list lst, return a new list that has two copies of every element in lst.
• Examples:

  double [1;2;3;4] = [1;1;2;2;3;3;4;4]
  double ["a"; "b"; "c"] = ["a"; "a"; "b"; "b"; "c"; "c"]