Purescript Justifill
This module provides three interesting functions:
- fill Which adds Nothings to records with missing fields
- justify Which turns non-Maybe values into Justs
- and justifill which combines the two
Examples:
filled :: { name :: Maybe String, id :: Int }
filled = fill { id: 10 }
-- { name: Nothing, id: 10 }justified :: { name :: Maybe String, age :: Maybe Int }
justified = justify { name: "Mark", age: 40 }
-- { name: Just "Mark", age: Just 40 }justifilled :: { name :: Maybe String, age :: Maybe Int, id :: Int }
justifilled = justifill { name: "Mark", id: 12 }
-- { name: Just "Mark", age: Nothing, id: 12 }Use cases
This can be handy when using APIs with many optional inputs (Props in React Components for example).
Combined with simple-json it can also be a viable alternative to something like purescript-options:
You can type your options as simple records with Maybes for non-mandatory fields:
foreign import someJSImpl :: Foreign -> Effect Unit
type SomeJSOptions =
{ option1 :: Maybe Int
, option2 :: Maybe Number
-- ...
, option304 :: Maybe String
, mandatory :: String }
someJS :: SomeJSOptions -> Effect Unit
someJS = write >>> someJSImpl
-- Usage:
result = someJS (justifill { mandatory: "Hi", option302: "Woah!" })
