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101 lines
4.0 KiB
Markdown
101 lines
4.0 KiB
Markdown
# Autodocodec
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Autodocodec is short for "self(auto)- documenting encoder and decoder".
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In short:
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You write a single instance, of the 'Codec' type-class, for your type, and you get:
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* [A 'ToJSON' instance from 'aeson' with both a `toJSON` and `toEncoding` implementation](https://hackage.haskell.org/package/aeson-2.0.1.0/docs/Data-Aeson-Types.html#t:ToJSON)
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* [A 'FromJSON' instance from 'aeson'](https://hackage.haskell.org/package/aeson-2.0.1.0/docs/Data-Aeson-Types.html#t:FromJSON)
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* [A 'ToYaml' instance from 'yaml'](https://hackage.haskell.org/package/yaml-0.11.7.0/docs/Data-Yaml-Builder.html#t:ToYaml)
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* [A json schema](http://json-schema.org/)
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* [A nicely-coloured human-readable yaml schema](./autodocodec-yaml)
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* [A Swagger schema](https://swagger.io/specification/v2/)
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* [An Openapi schema](https://swagger.io/specification/)
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See [the golden test directory](./autodocodec-api-usage/test_resources) directory for example outputs.
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## Features
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* ✓ Correct-by-construction encoding and decoding, without generating code.
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* ✓ Generate automatically-correct documentation from code.
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* ✓ Support for recursive types.
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## State of this project
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This project is ready to try out!
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## Fully featured example
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``` haskell
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{-# LANGUAGE DeriveGeneric #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE DerivingVia #-}
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{-# LANGUAGE TypeApplications #-}
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module Main (main) where
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import Autodocodec
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import Autodocodec.Yaml
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import GHC.Generics
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import Data.Aeson (FromJSON, ToJSON)
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import Data.Text (Text)
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import qualified Data.Text as T
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data Example = Example
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{ exampleTextField :: !Text,
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exampleIntField :: !Int
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}
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deriving stock (Show, Eq, Generic)
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deriving
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( FromJSON, -- <- FromJSON instance for free.
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ToJSON -- <- ToJSON instance for free.
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)
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via (Autodocodec Example)
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instance HasCodec Example where
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codec =
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object "Example" $
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Example
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<$> requiredField "text" "documentation for the text field" .= exampleTextField
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<*> requiredField "int" "documentation for the int field" .= exampleIntField
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main :: IO ()
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main = do
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let schema = T.unpack $ renderColouredSchemaViaCodec @Example
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putStrLn schema
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```
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This will output a nice coloured yaml-schema:
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```
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# Example
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text: # required
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# documentation for the text field
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<string>
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int: # required
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# documentation for the int field
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<number> # between -9223372036854775808 and 9223372036854775807
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```
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## Tests
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While we don't provide any actual guarantees, we do have tests for the following properties that we would like to maintain:
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* [Encoding and decoding roundtrips through JSON.](./autodocodec-api-usage/test/Autodocodec/AesonSpec.hs)
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* [For standard types, encoding behaves in the same way that `aeson` does.](./autodocodec-api-usage/test/Autodocodec/AesonSpec.hs)
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* [Error messages for decoding are still good.](./autodocodec-api-usage/test/Autodocodec/AesonSpec.hs)
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* [Generated Human-readible documentation looks good.](./autodocodec-api-usage/test/Autodocodec/Yaml/DocumentSpec.hs)
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* [Generated JSON schemas look good.](./autodocodec-api-usage/test/Autodocodec/Aeson/SchemaSpec.hs)
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* [Generated Swagger schemas look good.](./autodocodec-api-usage/test/Autodocodec/SwaggerSpec.hs)
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* [Generated OpenAPI schemas look good.](./autodocodec-api-usage/test/Autodocodec/OpenAPISpec.hs)
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* [Generated values are accepted by the corresponding generated JSON schemas.](./autodocodec-api-usage/test/Autodocodec/Aeson/SchemaSpec.hs)
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* [Generated values are accepted by the corresponding generated Swagger schemas.](./autodocodec-api-usage/test/Autodocodec/SwaggerSpec.hs)
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* [Generated values are accepted by the corresponding generated OpenAPI schemas.](./autodocodec-api-usage/test/Autodocodec/OpenAPISpec.hs)
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* [Encoding and decoding roundtrips through YAML.](./autodocodec-api-usage/test/Autodocodec/YamlSpec.hs)
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* [We try to make sure that backward compatibility is maintained.](./autodocodec-api-usage/src/Autodocodec/Usage.hs)
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* [Codecs are more or less inspectable.](./autodocodec-api-usage/test/Autodocodec/ShowSpec.hs)
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* [Encoding and decoding is still fast](./autodocodec-api-usage/bench/Main.hs)
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