F# · Easy

Lesson 1 · On the house

Sequences and laziness

seq expressions, Seq module, infinite sequences, and caching.

Lesson 2

Map and Set

Immutable dictionaries and sets: add, tryFind, change, union, and difference.

Lesson 3

Strings and text

sprintf, String module, .NET string methods, slicing, and triple-quoted strings.

Lesson 4

Result for errors

Ok and Error, Result.map, Result.bind, and railway-style validation.

Lesson 5

Modules and organisation

module, namespaces, private helpers, open, and file order in projects.

Lesson 6

Arrays and mutation

Fixed-size mutable arrays, Array module, in-place sort, and 2D arrays.

Lesson 7

Folding and grouping

fold, reduce, scan, groupBy, countBy, sumBy, and maxBy.

Lesson 8

Exceptions

failwith, raise, try/with, try/finally, custom exceptions, and use for disposal.

Lesson 9

Classes and members

Primary constructors, members, properties, mutable state, and static members.

Lesson 10

Interfaces and object expressions

Define interfaces, implement them on types, and create one-off objects inline.