purescript / purescript-record

Functions for working with records and polymorphic labels

purescript-record

Functions for working with records and polymorphic labels

Installation

spago install record

Examples

Given some Symbol ("type level String") Proxy and a constrained or concrete record type, you can use this library to generically modify records.

x_ = Proxy :: Proxy "x"

-- we can get a value out of a field
gotX :: Int
gotX = Record.get x_ { x: 1 }

-- we can insert a value into a record that does not have a field at that label yet
insertedX :: { x :: Int }
insertedX = Record.insert x_ 1 {}

-- we can delete a field from a record at a specific label
deletedX :: {}
deletedX = Record.delete x_ { x: 1 }

-- we can set a new value for a field
setX1 :: { x :: Int }
setX1 = Record.set x_ 1 { x: 0 }

-- we can also modify the type of the field by replacing the contents
setX2 :: { x :: Unit }
setX2 = Record.set x_ unit { x: 0 }

-- we can modify the field value with a function
modifyX :: { x :: Int }
modifyX = Record.modify x_ (\value -> value + 1) { x: 0 }

-- we can also merge two records
mergedXY :: { x :: Int , y :: Int }
mergedXY = Record.merge { x: 1 } { y: 1 }

See the tests for more examples.

If you need to combine multiple operations and avoid intermediate values, you might consider using Record.Builder.

You can also find an explanation and example of how to use this library in this tutorial of the Simple-JSON docs.

Documentation

Module documentation is published on Pursuit.