pinch
aims to provide an alternative implementation of Apache Thrift for
Haskell. The pinch
library itself acts only as a serialization library. Types
specify their Thrift encoding by defining instances of the Pinchable
typeclass, which may be done by hand or automatically with the use of Generics.
Haddock documentation for this package is avilable on Hackage and here.
Overview
Types which can be encoded into Thrift payloads implement the Pinchable
typeclass.
Given the Thrift struct,
struct Person {
1: required string name
2: optional i64 dateOfBirth
}
You can write a Pinchable
instance like so,
data Person = Person { name :: Text, dateOfBirth :: Maybe Int64 }
deriving (Eq)
instance Pinchable Person where
type Tag Person = TStruct
-- The Tag tells the system that this represents a struct.
pinch (Person name dateOfBirth) =
struct [1 .= name, 2 ?= dateOfBirth]
unpinch value =
Person <$> value .: 1
<*> value .:? 2
Better yet, you can drive an instance automatically.
{-# LANGUAGE DeriveGeneric, DataKinds #-}
import GHC.Generics (Generic)
data Person = Person
{ name :: Field 1 Text
, dateOfBirth :: Field 2 (Maybe Int64)
} deriving (Eq, Generic)
instance Pinchable Person
Objects can be serialized and deserialized using the encode
and decode
methods. These methods accept a Protocol
as an argument.
decode binaryProtocol (encode binaryProtocol person) == person
For more information, check the documentation and the examples.
Supported Protocols
The following Thrift protocols are supported:
Caveats
- There is no code generation or template haskell support yet so types from
the Thrift file will have to be translated by hand.