https://github.com/vladimirlogachev/transitive-closure

Coding assessment (Scala 3, Cats, ScalaTest) 2019
https://github.com/vladimirlogachev/transitive-closure

Last synced: 19 days ago
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Coding assessment (Scala 3, Cats, ScalaTest) 2019

• Host: GitHub
• URL: https://github.com/vladimirlogachev/transitive-closure
• Owner: vladimirlogachev
• Created: 2019-10-07T15:39:46.000Z (about 5 years ago)
• Default Branch: main
• Last Pushed: 2024-11-02T05:32:34.000Z (about 2 months ago)
• Last Synced: 2024-11-30T05:28:57.611Z (24 days ago)
• Language: Scala
• Homepage:
• Size: 30.3 KB
• Stars: 1
• Watchers: 1
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# transitive-closure

Coding assessment (Scala 3, Cats, ScalaTest).

Completed in 2019, and currently maintained as a demonstration project.

## Pre-requisites

- [sbt](https://www.scala-sbt.org/)

## Usage

- `sbt test` - test

- `sbt styleFix` - fix formatting and linting errors

- `sbt styleCheck` - check for formatting and linting errors

- `sbt dev` - allow compiler warnings to not fail the compilation

## Objective

A database contains `Foo` items, and all their `references` do exist in db. One can use `FooRepository` interface to interact with db.

The task is to implement a `readClosure` function, which accepts a list of `FooId` and returns them and all objects which they refer to (directly or indirectly). The function should be tested with mock implementations of `FooRepository` (which should also be developed).

 

## Technical decisions

### 1. Tail recursive monadic function is used

This allows large relation graphs

### 2. Cyclic relations are allowed

Items can refer to each other in any order

### 3. Each item will be requested exactly once

This was not required by the objective. However, since all elements are merged in a single Set, there will ever be no need in fetching some element twice, that's why this restriction was added (and tested). Also this makes sense in case of ring-like relations.