exercism/clojure/lucians-luscious-lasagna

Lucian's Luscious Lasagna

Welcome to Lucian's Luscious Lasagna on Exercism's Clojure Track. If you need help running the tests or submitting your code, check out HELP.md. If you get stuck on the exercise, check out HINTS.md, but try and solve it without using those first :)

Introduction

In Clojure, binding a value to a name is referred to as a var. Top-level (global) vars are similar to constants in other languages, but are commonly redefined to facilitate dynamic development.

Top-level vars are defined using def:

(def fingers 10)

The defn macro can be used to define a function taking zero or more arguments. A function always returns the result of the last expression in its body.

(defn add [x y]
  (+ x y))

Invoking a function is done by specifying its name and passing arguments for each of the function's parameters.

(def five (add 2 3))

Functions and values in Clojure can only be used after they have been defined. Using it before it has been defined results in a compile error.

;; Compile error as `add` has not yet been defined
(def seven (add 3 4))

(defn add [x y]
  (+ x y))

In Clojure, whitespace has no significance other than formatting.

Clojure functions and vars are organized in namespaces. A namespace groups related functionality and is defined using the ns macro:

(ns calculator)

(def pi 3.14)

(defn add [x y]
  (+ x y))

Clojure supports two types of comments. Single line comments are preceded by ; and the comment form is used to prevent evaluation of everything between (comment and ).

Instructions

In this exercise you're going to write some code to help you cook a brilliant lasagna from your favorite cooking book.

You have four tasks, all related to the time spent cooking the lasagna.

1. Define the expected oven time in minutes

Define the expected-time var to check how many minutes the lasagna should be in the oven. According to the cooking book, the expected oven time in minutes is 40:

expected-time
;;=> 40

2. Calculate the remaining oven time in minutes

Define the remaining-time function that takes the actual minutes the lasagna has been in the oven as an argument and returns how many minutes the lasagna still has to remain in the oven, based on the expected time oven time in minutes from the previous task.

(remaining-time 30)
;;=> 10

3. Calculate the preparation time in minutes

Define the prep-time function that takes the number of layers you added to the lasagna as an argument and returns how many minutes you spent preparing the lasagna, assuming each layer takes you 2 minutes to prepare.

(prep-time 2)
;;=> 4

4. Calculate the total working time in minutes

Define the total-time function that takes two arguments: the first argument is the number of layers you added to the lasagna, and the second argument is the number of minutes the lasagna has been in the oven. The function should return how many minutes in total you've worked on cooking the lasagna, which is the sum of the preparation time in minutes, and the time in minutes the lasagna has spent in the oven at the moment.

(total-time 3 20)
;;=> 26

Source

Created by

• @porkostomus