Option.map

As explained in F# in Action: A Revised Edition of Get Programming with F#

Option.map is an F# library function that applies a function to the value in a Some case and returns None unchanged, wrapping a successful result in Some.

Working with optional data often creates repetitive pattern matches: unwrap a Some value, apply the business logic, then wrap the result again. Option.map removes that boilerplate while preserving the possibility of None. section 9.1.3

Option.map takes a function for the Some case. It applies that function when a value exists, wraps the result in Some, and leaves None unchanged. Ordinary functions therefore work with optional values without knowing about options. section 9.1.3

A manual transformation can be reduced to a pipeline:

• Verbose form: match customer with | Some c -> Some c.Age | None -> None. section 9.1.3
• Idiomatic form: customer |> Option.map (fun c -> c.Age). section 9.1.3
• Chain transformations with customer |> Option.map getAge |> Option.map classifyAge; each step continues only when the option contains Some. section 9.1.3

Compose before mapping

When getAge returns an int and classifyAge accepts an int, combine them as optionalCustomer |> Option.map (getAge >> classifyAge). This maps the option once and keeps getAge and classifyAge independent of optionality. section 9.1.3

Figure 9.2 A pipeline of operations over optional data

Trace how a pipeline of operations transforms optional data while preserving the option container. section 9.1.3

How F# in Action: A Revised Edition of Get Programming with F# covers it

How deep it goes

Explains unwrapping, mapping, rewrapping, chaining, and composition, but defers deeper treatment to Option.bind.

Examples

Uses customer ages, age classification, manual matches, chained pipelines, and composed functions.

What it assumes

Assumes familiarity with F# functions, options, Some and None, and basic pattern matching.

What you can do after

Apply it via F# pipelines to transform Some values without manually unwrapping and rewrapping options.

How it connects

Connects Option.map with Option, Option.bind, pattern matching, function composition, Result, and exceptions.

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Related concepts

• optionused by · An option type is a type that explicitly represents either a value of a specified type or the absence of a value.
• functionuses · A function is a callable program unit that performs an operation, may accept inputs, and can produce a result or side effect.
• pattern matchingalternative to · Pattern matching is the process of comparing data or values with specified or learned patterns to identify correspondence, conformity, or a matching case.
• mapequivalent to · An operation that applies a function to values in a collection or computational context, producing corresponding results while preserving the collection or context’s structure.

This explainer was generated by Manning's knowledge graph from the text of F# in Action: A Revised Edition of Get Programming with F#. The section links point to the parts of the book it draws on.