Implement new Concept Exercise: function-composition

[ErikSchierboom]

This issue describes how to implement the function-composition concept exercise for the F# track.

Getting started

Please please please read the docs before starting. Posting PRs without reading these docs will be a lot more frustrating for you during the review cycle, and exhaust Exercism's maintainers' time. So, before diving into the implementation, please read up on the following documents:

• The features of v3.
• Rationale for v3.
• What are concept exercise and how they are structured?

Please also watch the following video:

• The Anatomy of a Concept Exercise.

Goal

The goal of this exercise is to teach the student more advanced aspects of the Concept of Composition in F#.

Learning objectives

• Know what function associativity is.
• Know how to compose functions.
• Know what partial application is and how to use it.
• Know what currying is and how it is used in F#.
• Know how to use the pipeline operator.

Out of scope

• Recursion.
• Computation expressions.

Concepts

The Concepts this exercise unlocks are:

• function-composition: know what function associativity is; know how to compose functions; know what partial application is and how to use it; know what currying is and how it is used in F#; know how to use the pipeline operator.

Prerequisites

This exercise's prerequisites Concepts are:

• higher-order-functions: know how to use higher-order functions.

Any data types used in this exercise (e.g. strings or booleans) should also be added as prerequisites.

Resources to refer to

Hints

• Composition and pipelining: introduction to composition and pipelining.
• Partial application: introduction to partial application.

After

• Composition and pipelining: introduction to composition and pipelining.
• Partial application: introduction to partial application.
• Composition in-depth: in-depth explanation of composition.
• Partial application-in-depth: in-depth explanation of partial application.
• Currying in-depth: in-depth explanation of currying.

Representer

This exercise does not require any specific representation logic to be added to the representer.

Analyzer

This exercise does not require any specific logic to be added to the analyzer.

Implementing

To implement this exercise, please follow these instructions.

Help

If you have any questions while implementing the exercise, please post the questions as comments in this issue.