Data.Record.Optionality

This module provides support for optionality records.

Optionality records are used to specify interfaces with optional input data. Compared to an ordinary record type, an optionality record type states for every field whether it is required or optional. This is done by a slight abuse of field names. A field name name is replaced by either Req name or Opt name. Optionality record types are never used directly in types of actual values. Instead, they are converted into ordinary record types with the type functions All and Required.

Documentation

data Req name

A marker for required fields.

Instances

OptRecord optRecord => OptRecord (:& optRecord (::: (Req name) sort))

data Opt name

A marker for optional fields.

Instances

OptRecord optRecord => OptRecord (:& optRecord (::: (Opt name) sort))

class OptRecord optRecord

The class of all optionality record types.

Associated Types

type All optRecord :: * -> *

Converts an optionality record type into an ordinary record type by dropping all Req and Opt annotations.

type Required optRecord :: * -> *

Extracts all required fields from an optionality record type and drops their Req annotations.

Instances

OptRecord X

OptRecord optRecord => OptRecord (:& optRecord (::: (Opt name) sort))

OptRecord optRecord => OptRecord (:& optRecord (::: (Req name) sort))