aws-arn

This library provides a type representing Amazon Resource Names (ARNs), and parsing/unparsing functions for them. The provided optics make it very convenient to rewrite parts of ARNs.

Start reading at the Network.AWS.ARN module, which defines the core data type and includes some examples.

The ARN type is not designed to be a 100% correct-by-construction representation of only valid ARNs; it is designed to be a lightweight way to destructure and reassemble ARNs to be used in place of string munging.

The library aims to provide additional parsers for destructuring the "resource" part of an ARN, but many are missing right now. PRs to add this support for more AWS resource types are especially welcome.

Guide: adding a resource

Cribbing from an existing module (e.g., Network.AWS.ARN.Lambda) is probably the easiest way to start, but here is an explicit process to add a new resource:

1. Create a module for the AWS service, if it doesn't already exist. Example: src/Network/AWS/ARN/Lambda.hs.

2. Define a record Foo to represent the parsed resource part of an ARN, and derive (at least) Eq, Ord, Hashable, Show and Generic. Also generate lenses for its fields:

   data Function = Function
   { _fName :: Text,
     _fQualifier :: Maybe Text
   }
   deriving (Eq, Ord, Hashable, Show, Generic)
   
   $(makeLenses ''Function)
   

3. Define toFoo and fromFoo functions that attempt to parse and unparse the resource part of the ARN:

   toFunction :: Text -> Maybe Function
   fromFunction :: Function -> Text
   

   Remark: While these names sound backwards compared to fromText and toText, it means we can have multiple parsing functions in a single service's module.

   Remark: If you need to write tests for these functions, the corresponding module should live at test/Network/AWS/ARN/SomeAWSService/Test.hs

4. Define a _Foo Prism' that combines the parsing/unparsing functions above:

   _Function :: Prism' Text Function
   _Function = prism' fromFunction toFunction
   

5. Add the records, its fields, its parsing/unparsing functions, and its optics to the service module's export list:

   module Network.AWS.ARN.Lambda
     ( -- * Functions
       Function (..),
       toFunction,
       fromFunction,
   
       -- ** Function Optics
       _Function,
       fName,
       fQualifier,
     )
   

6. Test your work and make a PR.

Formatters

The formatters used in this repo are provided by shell.nix:

• *.hs: ormolu
• *.cabal: cabal-fmt (cabal-fmt --inplace wai-handler-hal.cabal)
• *.nix: nixpkgs-fmt (nixpkgs-fmt *.nix)

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