Implement new Concept Exercise: type-inference

[ErikSchierboom]

This issue describes how to implement the type-inference 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 the basics of the Concept of Type Inference in F#.

Learning objectives

• Know what type-inference is
• Know how type-inference works.
• Know on what values type inference works (including records, tuples and discriminated unions).
• Know about the limitations of type inference and how to work around them.
• Know what automatic generalization is.
• Know what generic functions are.

Out of scope

• Performance aspects.

Concepts

The Concepts this exercise unlocks are:

• type-inference: know what type-inference is; know how type-inference works; know on what values type inference works; know about the limitations of type inference and how to work around them; know what automatic generalization is.
• generic-functions: know what generic functions are.

Prerequisites

This exercise's prerequisites Concepts are:

• records: know what records are.
• tuples: know what tuples are.
• discriminated-unions: know what discriminated unions are.
• higher-order-functions: know how to read function type signatures.

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

Resources to refer to

Hints

• Type inference: introduction to type inference.
• Type inference for functions: how type inference works for functions.
• Automatic generalization: what automatica generalization is and how to use it.

After

• Type inference: introduction to type inference.
• Type inference for functions: how type inference works for functions.
• Automatic generalization: what automatica generalization is and how to use it.
• Type inference in-depth: in-depth look at type-inference.

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.