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Optics for schema and gRPC clients (#102)

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packages: compendium-client/
core/schema/
core/rpc/
core/optics/
adapter/avro/
adapter/protobuf/
adapter/persistent/

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cradle: { stack: { component: "mu-optics:lib" } }

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cabal-version: >=1.10
name: mu-optics
version: 0.1.0.0
synopsis: Optics for @mu-schema@ terms
description: With @mu-schema@ you can describe schemas using type-level constructs, and derive serializers from those. This package provides convenient access using @optics@.
license: Apache-2.0
license-file: LICENSE
author: Alejandro Serrano
maintainer: alejandro.serrano@47deg.com
copyright: Copyright © 2019-2020 <http://47deg.com 47 Degrees>
category: Network
build-type: Simple
homepage: https://higherkindness.io/mu-haskell/
bug-reports: https://github.com/higherkindness/mu-haskell/issues
source-repository head
type: git
location: https://github.com/higherkindness/mu-haskell
library
exposed-modules: Mu.Schema.Optics
-- other-modules:
-- other-extensions:
build-depends: base >=4.12 && <5
, sop-core
, optics-core
, mu-schema
, containers
hs-source-dirs: src
default-language: Haskell2010
ghc-options: -Wall

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{-# language DataKinds #-}
{-# language FlexibleInstances #-}
{-# language FunctionalDependencies #-}
{-# language GADTs #-}
{-# language KindSignatures #-}
{-# language ScopedTypeVariables #-}
{-# language TypeApplications #-}
{-# language TypeOperators #-}
{-# language UndecidableInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
{-|
Description : Optics-based interface for @mu-schema@ terms
This module provides instances of 'LabelOptic' to be
used in conjunction with the @optics@ package.
In particular, there are two kind of optics to access
different parts of a 'Term':
* With @#field@ you obtain the lens (that is, a getter
and a setter) for the corresponding field in a record.
* With @#choice@ you obtain the prism for the
desired choice in an enumeration. You can use then
'review' to construct a term with the value.
In addition, we provide a utility function 'record' to
build a record out of the inner values. We intend the
interface to be very simple, so this function is overloaded
to take tuples of different size, with as many components
as values in the schema type.
-}
module Mu.Schema.Optics (
-- * Build a term
record
-- * Re-exported for convenience.
, module Optics.Core
) where
import Data.Functor.Identity
import Data.Kind
import Data.Map
import Data.Proxy
import GHC.TypeLits
import Optics.Core
import Mu.Schema
instance {-# OVERLAPS #-}
(FieldLabel Identity sch args fieldName r)
=> LabelOptic fieldName A_Lens
(Term Identity sch ('DRecord name args))
(Term Identity sch ('DRecord name args))
r r where
labelOptic = lens (\(TRecord r) -> runIdentity $ fieldLensGet (Proxy @fieldName) r)
(\(TRecord r) x -> TRecord $ fieldLensSet (Proxy @fieldName) r (Identity x))
instance {-# OVERLAPPABLE #-}
(FieldLabel w sch args fieldName r, t ~ w r)
=> LabelOptic fieldName A_Lens
(Term w sch ('DRecord name args))
(Term w sch ('DRecord name args))
t t where
labelOptic = lens (\(TRecord r) -> fieldLensGet (Proxy @fieldName) r)
(\(TRecord r) x -> TRecord $ fieldLensSet (Proxy @fieldName) r x)
record :: BuildRecord w sch args r => r -> Term w sch ('DRecord name args)
record values = TRecord $ buildR values
class BuildRecord (w :: Type -> Type)
(sch :: Schema Symbol Symbol)
(args :: [FieldDef Symbol Symbol])
(r :: Type) | w sch args -> r where
buildR :: r -> NP (Field w sch) args
instance BuildRecord w sch '[] () where
buildR _ = Nil
instance (Functor w, TypeLabel w sch t1 r1)
=> BuildRecord w sch '[ 'FieldDef x1 t1 ] (w r1) where
buildR v = Field (typeLensSet <$> v) :* Nil
instance (Functor w, TypeLabel w sch t1 r1, TypeLabel w sch t2 r2)
=> BuildRecord w sch '[ 'FieldDef x1 t1, 'FieldDef x2 t2 ] (w r1, w r2) where
buildR (v1, v2) = Field (typeLensSet <$> v1)
:* Field (typeLensSet <$> v2) :* Nil
instance (Functor w, TypeLabel w sch t1 r1, TypeLabel w sch t2 r2, TypeLabel w sch t3 r3)
=> BuildRecord w sch
'[ 'FieldDef x1 t1, 'FieldDef x2 t2, 'FieldDef x3 t3 ]
(w r1, w r2, w r3) where
buildR (v1, v2, v3) = Field (typeLensSet <$> v1)
:* Field (typeLensSet <$> v2)
:* Field (typeLensSet <$> v3) :* Nil
class FieldLabel (w :: Type -> Type)
(sch :: Schema Symbol Symbol)
(args :: [FieldDef Symbol Symbol])
(fieldName :: Symbol) (r :: Type)
| w sch args fieldName -> r where
fieldLensGet :: Proxy fieldName -> NP (Field w sch) args -> w r
fieldLensSet :: Proxy fieldName -> NP (Field w sch) args -> w r -> NP (Field w sch) args
{- Removed due to FunDeps
instance TypeError ('Text "cannot find field " ':<>: 'ShowType f)
=> FieldLabel w sch '[] f t where
fieldLensGet = error "this should never be run"
fieldLensSet = error "this should never be run"
-}
instance {-# OVERLAPS #-} (Functor w, TypeLabel w sch t r)
=> FieldLabel w sch ('FieldDef f t ': rest) f r where
fieldLensGet _ (Field x :* _) = typeLensGet <$> x
fieldLensSet _ (_ :* r) new = Field (typeLensSet <$> new) :* r
instance {-# OVERLAPPABLE #-} FieldLabel w sch rest g t
=> FieldLabel w sch (f ': rest) g t where
fieldLensGet p (_ :* r) = fieldLensGet p r
fieldLensSet p (x :* r) new = x :* fieldLensSet p r new
class TypeLabel w (sch :: Schema Symbol Symbol) (t :: FieldType Symbol) (r :: Type)
| w sch t -> r where
typeLensGet :: FieldValue w sch t -> r
typeLensSet :: r -> FieldValue w sch t
instance TypeLabel w sch ('TPrimitive t) t where
typeLensGet (FPrimitive x) = x
typeLensSet = FPrimitive
instance (r ~ (sch :/: t)) => TypeLabel w sch ('TSchematic t) (Term w sch r) where
typeLensGet (FSchematic x) = x
typeLensSet = FSchematic
instance (TypeLabel w sch o r', r ~ Maybe r')
=> TypeLabel w sch ('TOption o) r where
typeLensGet (FOption x) = typeLensGet <$> x
typeLensSet new = FOption (typeLensSet <$> new)
instance (TypeLabel w sch o r', r ~ [r'])
=> TypeLabel w sch ('TList o) r where
typeLensGet (FList x) = typeLensGet <$> x
typeLensSet new = FList (typeLensSet <$> new)
instance ( TypeLabel w sch k k', TypeLabel w sch v v'
, r ~ Map k' v', Ord k', Ord (FieldValue w sch k) )
=> TypeLabel w sch ('TMap k v) r where
typeLensGet (FMap x) = mapKeys typeLensGet (typeLensGet <$> x)
typeLensSet new = FMap (mapKeys typeLensSet (typeLensSet <$> new))
instance (EnumLabel choices choiceName, r ~ ())
=> LabelOptic choiceName A_Prism
(Term w sch ('DEnum name choices))
(Term w sch ('DEnum name choices))
r r where
labelOptic = prism' (\_ -> TEnum $ enumPrismBuild (Proxy @choiceName))
(\(TEnum r) -> enumPrismMatch (Proxy @choiceName) r)
class EnumLabel (choices :: [ChoiceDef Symbol])
(choiceName :: Symbol) where
enumPrismBuild :: Proxy choiceName -> NS Proxy choices
enumPrismMatch :: Proxy choiceName -> NS Proxy choices -> Maybe ()
instance TypeError ('Text "cannot find choice " ':<>: 'ShowType c)
=> EnumLabel '[] c where
enumPrismBuild = error "this should never be run"
enumPrismMatch = error "this should never be run"
instance {-# OVERLAPS #-} EnumLabel ('ChoiceDef c ': rest) c where
enumPrismBuild _ = Z Proxy
enumPrismMatch _ (Z _) = Just ()
enumPrismMatch _ _ = Nothing
instance {-# OVERLAPPABLE #-} EnumLabel rest c
=> EnumLabel (d ': rest) c where
enumPrismBuild p = S (enumPrismBuild p)
enumPrismMatch _ (Z _) = Nothing
enumPrismMatch p (S x) = enumPrismMatch p x

13
core/schema/src/Mu/Schema/Class.hs
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@ -86,6 +86,19 @@ class FromSchema (w :: Type -> Type) (sch :: Schema typeName fieldName) (sty ::
=> Term w sch (sch :/: sty) -> t
fromSchema x = to (fromSchemaTypeDef (Proxy @'[]) x)
instance (sch :/: sty ~ 'DRecord sty fields)
=> ToSchema w sch sty (Term w sch ('DRecord sty fields)) where
toSchema = id
instance (sch :/: sty ~ 'DEnum sty choices)
=> ToSchema w sch sty (Term w sch ('DEnum sty choices)) where
toSchema = id
instance (sch :/: sty ~ 'DRecord sty fields)
=> FromSchema w sch sty (Term w sch ('DRecord sty fields)) where
fromSchema = id
instance (sch :/: sty ~ 'DEnum sty choices)
=> FromSchema w sch sty (Term w sch ('DEnum sty choices)) where
fromSchema = id
-- | Conversion from Haskell type to schema term.
-- This version is intended for usage with @TypeApplications@:
-- > toSchema' @MySchema myValue

9
core/schema/src/Mu/Schema/Definition.hs
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@ -135,6 +135,15 @@ data FieldTypeB builtin typeName
-- | Represents a choice between types.
| TUnion [FieldTypeB builtin typeName]
instance KnownName n => KnownName ('DRecord n fields) where
nameVal _ = nameVal (Proxy @n)
instance KnownName n => KnownName ('DEnum n choices) where
nameVal _ = nameVal (Proxy @n)
instance KnownName n => KnownName ('ChoiceDef n) where
nameVal _ = nameVal (Proxy @n)
instance KnownName n => KnownName ('FieldDef n t) where
nameVal _ = nameVal (Proxy @n)
-- | Lookup a type in a schema by its name.
type family (sch :: Schema t f) :/: (name :: t) :: TypeDef t f where
'[] :/: name = TypeError ('Text "Cannot find type " ':<>: 'ShowType name ':<>: 'Text " in the schema")

1
default.nix
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@ -21,4 +21,5 @@ in {
mu-protobuf = hnPkgs.mu-protobuf.components.all;
mu-rpc = hnPkgs.mu-rpc.components.library;
mu-schema = hnPkgs.mu-schema.components.library;
mu-optics = hnPkgs.mu-optics.components.library;
}

73
docs/docs/grpc.md
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@ -36,7 +36,7 @@ import System.Environment
main :: IO ()
main = do
let config = grpcClientConfigSimple "127.0.0.1" 8080 False
Right client <- setupGrpcClient' config
Right client <- setup config
args <- getArgs
case args of
["watch"] -> watching client
@ -45,11 +45,53 @@ main = do
_ -> putStrLn "unknown command"
```
Where `watch`, `get` and `add` are the only valid 3 commands that our CLI is going to accept and call each respective service.
Where `watch`, `get` and `add` are the only valid 3 commands that our CLI is going to accept and call each respective service. The `setup` function is responsible from initializing the
### Using optics
The simplest way to call methods is to use the `optics`-based API. In that case, your setup is done using `initGRpc`, which receives the configuration.
```haskell
main :: IO ()
main = do ...
where setup config = initGRpc config
```
To call a method, you use the corresponding getter (for those familiar with optics, a version of a lens which does not allow to set). This means that your code reads `client ^. #method`, where `client` is the value obtained previously in the call to `initGRpc`.
```haskell
{-# language OverloadedLabels #-}
import Text.Read (readMaybe)
get :: GRpcConnection QuickstartService -> String -> IO ()
get client idPerson = do
let req = record (readMaybe idPerson)
putStrLn $ "GET: is there some person with id: " ++ idPerson ++ "?"
res <- (client ^. #getPerson) req
putStrLn $ "GET: response was: " ++ show res
```
Notice the use of `readMaybe` to convert the strings to the appropiate type in a safe manner! 👆🏼
Using this approach you must also use the optics-based interface to the terms. As a quick reminder: you use `record` to build new values, and use `value ^. #field` to access a field. The rest of the methods look as follows:
```haskell
add :: GRpcConnection QuickstartService -> String -> String -> IO ()
add client nm ag = do
let p = record (Nothing, Just $ T.pack nm, readMaybe ag)
putStrLn $ "ADD: creating new person " ++ nm ++ " with age " ++ ag
res <- (client ^. #newPerson) p
putStrLn $ "ADD: was creating successful? " ++ show res
watching :: GRpcConnection QuickstartService -> IO ()
watching client = do
replies <- client ^. #allPeople
runConduit $ replies .| C.mapM_ print
```
### Using records
This option is a bit more verbose but it's also more explicit with the types and _"a bit more magic"_ than the one with `TypeApplications` (due to the use of Generics).
This option is a bit more verbose but it's also more explicit with the types. Furthermore, it allows us to use our Haskell data types, we are not forced to use plain terms. As discussed several times, this is important to ensure that Haskell types are not mere shadows of the schema types.
We need to define a new record type (hence the name) that declares the services our client is going to consume. The names of the fields **must** match the names of the methods in the service, optionally prefixed by a **common** string. The prefix may also be empty, which means that the names in the record are exactly those in the service definition. In this case, we are prepending `call_` to each of them:
@ -64,36 +106,28 @@ data Call = Call
} deriving Generic
```
Note that we had to derive `Generic`. We also need to tweak our `main` function a little bit:
Note that we had to derive `Generic`. We also need to tweak our `setup` function a little bit:
```haskell
{-# language TypeApplications #-}
```diff
main :: IO ()
main = do
let config = grpcClientConfigSimple "127.0.0.1" 1234 False
- Right client <- setupGrpcClient' config
+ Right grpcClient <- setupGrpcClient' config
+ let client = buildService @Service @"call_" grpcClient
args <- getArgs
main = do ...
where setup config = buildService @Service @"call_" <$> setupGrpcClient' config
```
Instead of building our client directly, we need to call `buildService` (and enable `TypeApplications`) to create the actual gRPC client. There are two type arguments to be explicitly given: the first one is the `Service` definition we want a client for, and the second one is the prefix in the record (in our case, this is `call_`). In the case you want an empty prefix, you write `@""` in that second position.
After that, let's have a look at an example implementation of the three service calls:
After that, let's have a look at an example implementation of the three service calls. Almost as before, except that we use `call_` followed by the name of the method.
```haskell
import Text.Read (readMaybe)
get :: Call -> String -> IO ()
get client idPerson = do
let req = MPersonRequest $ readMaybe idPerson
putStrLn $ "GET: is there some person with id: " ++ idPerson ++ "?"
res <- call_getPerson client req
putStrLn $ "GET: response was: " ++ show res
```
Notice the use of `readMaybe` to convert the strings to the appropiate type in a safe manner! 👆🏼
```haskell
add :: Call -> String -> String -> IO ()
add client nm ag = do
let p = MPerson Nothing (Just $ T.pack nm) (readMaybe ag)
@ -117,6 +151,9 @@ If you are not familiar with `TypeApplications`, you can check [this](https://ww
```haskell
import Mu.GRpc.Client.TyApps
main = do ...
where setup config = setupGrpcClient' config
get :: GrpcClient -> String -> IO ()
get client idPerson = do
let req = MPersonRequest $ readMaybe idPerson

31
docs/docs/intro.md
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@ -23,7 +23,7 @@ The main goal of Mu-Haskell is to allow you to focus on your domain logic, inste
1. Create a new project with `stack new`.
2. Define your schema and your services in the `.proto` file.
3. Write your Haskell data types in `src/Schema.hs`.
3. Map to your Haskell data types in `src/Schema.hs`, or use optics.
4. Implement the server in `src/Main.hs`.
### Step by step
@ -53,7 +53,9 @@ The first step to get your project running is defining the right schema and serv
#### Data type definition
The second step is to define some Haskell data type corresponding to the message types in the gRPC definition. Although in some cases those data types can be inferred from the schema itself, we have made the design choice of having to write them explicitly, but check for compatibility at compile-time. The main goal is to discourage from making your domain types simple copies of the protocol types.
The second step is to define Haskell types corresponding to the message types in the gRPC definition. The recommended route is to create new Haskell data types and check for compatibility at compile-time. The goal is to discourage from making your domain types simple copies of the protocol types. Another possibility is to use the `optics` bridge and work with lenses for the fields.
##### Using Haskell types
The aforementioned `.proto` file defines two messages. The corresponding data types are as follows:
@ -81,6 +83,17 @@ You can give the data types and their constructors any name you like. However, k
* The name between quotes in each `deriving` clause defines the message type in the `.proto` file each data type corresponds to.
* To use the automatic-mapping functionality, it is required to also derive `Generic`, don't forget it!
##### Using optics
As we mentioned above, you may decide to not introduce new Haskell types, at the expense of losing some automatic checks against the current version of the schema. However, you gain access to a set of lenses and optics which can be used to inspect the values. In the Mu jargon, values from a schema which are not Haskell types are called *terms*, and we usually define type synonyms for each of them.
```haskell
type HelloRequestMessage' = Term Maybe TheSchema (TheSchema :/: "HelloRequest")
type HelloReplyMessage' = Term Maybe TheSchema (TheSchema :/: "HelloReply")
```
The arguments to `Term` closely correspond to those in `FromSchema` and `ToSchema` described above.
#### Server implementation
If you try to compile the project right now by means of `stack build`, you will receive an error about `server` not having the right type. This is because you haven't yet defined any implementation for your service. This is one of the advantages of making the compiler aware of your service definitions: if the `.proto` file changes, you need to adapt your code correspondingly, or otherwise the project doesn't even compile!
@ -95,7 +108,7 @@ server :: (MonadServer m) => ServerT Maybe Service m _
server = Server H0
```
The simplest way to provide an implementation for a service is to define one function for each method. You define those functions completely in terms of Haskell data types; in our case `HelloRequestMessage` and `HelloReplyMessage`. Here is an example definition:
The simplest way to provide an implementation for a service is to define one function for each method. You can define those functions completely in terms of Haskell data types; in our case `HelloRequestMessage` and `HelloReplyMessage`. Here is an example definition:
```haskell
sayHello :: (MonadServer m) => HelloRequestMessage -> m HelloReplyMessage
@ -105,7 +118,17 @@ sayHello (HelloRequestMessage nm)
The `MonadServer` portion in the type is mandated by `mu-rpc`; it tells us that in a method we can perform any `IO` actions and additionally throw server errors (for conditions such as *not found*). We do not make use of any of those here, so we simply use `return` with a value. We could even make the definition a bit more polymorphic by replacing `MonadServer` by `Monad`.
How does `server` know that `sayHello` is part of the implementation of the service? We have to tell it, by adding `sayHello` to the list of methods. Unfortunately, we cannot use a normal list, so we use `(:<|>:)` to join them, and `H0` to finish it.
Another possibility is to use the `optics`-based API in `Mu.Schema.Optics`. In that case, you access the value of the fields using `(^.)` followed by the name of the field after `#`, and build messages by using `record` followed by a tuple of the components. The previous example would then be written:
```haskell
{-# language OverloadedLabels #-}
sayHello :: (MonadServer m) => HelloRequestMessage' -> m HelloReplyMessage'
sayHello (HelloRequestMessage nm)
= return $ record (("hi, " <>) <$> (nm ^. #name))
```
How does `server` know that `sayHello` (any of the two versions) is part of the implementation of the service? We have to tell it, by adding `sayHello` to the list of methods. Unfortunately, we cannot use a normal list, so we use `(:<|>:)` to join them, and `H0` to finish it.
```haskell
server = Server (sayHello :<|>: H0)

17
examples/seed/mu-example-seed.cabal
View File

@ -28,3 +28,20 @@ executable seed-server
, mu-grpc-server
, text
, stm
executable seed-server-optics
hs-source-dirs: src
main-is: Optics.hs
other-modules: Schema
default-language: Haskell2010
build-depends: base >= 4.12 && < 5
, conduit
, monad-logger
, mu-schema
, mu-rpc
, mu-protobuf
, mu-optics
, mu-grpc-server
, text
, stm
ghc-options: -Wall -fprint-potential-instances

26
examples/seed/src/Main.hs
View File

@ -1,3 +1,7 @@
{-# language DataKinds #-}
{-# language DeriveAnyClass #-}
{-# language DeriveGeneric #-}
{-# language DuplicateRecordFields #-}
{-# language FlexibleContexts #-}
{-# language OverloadedStrings #-}
{-# language PartialTypeSignatures #-}
@ -10,12 +14,34 @@ import Control.Monad.IO.Class (liftIO)
import Control.Monad.Logger
import Data.Conduit
import Data.Conduit.Combinators as C
import Data.Int
import Data.Text as T
import GHC.Generics
import Mu.GRpc.Server
import Mu.Schema
import Mu.Server
import Schema
data Person = Person
{ name :: Maybe T.Text
, age :: Maybe Int32
} deriving ( Eq, Show, Ord, Generic
, ToSchema Maybe SeedSchema "Person"
, FromSchema Maybe SeedSchema "Person" )
newtype PeopleRequest = PeopleRequest
{ name :: Maybe T.Text
} deriving ( Eq, Show, Ord, Generic
, ToSchema Maybe SeedSchema "PeopleRequest"
, FromSchema Maybe SeedSchema "PeopleRequest" )
newtype PeopleResponse = PeopleResponse
{ person :: Maybe Person
} deriving ( Eq, Show, Ord, Generic
, ToSchema Maybe SeedSchema "PeopleResponse"
, FromSchema Maybe SeedSchema "PeopleResponse" )
main :: IO ()
main = do
putStrLn "running seed application"

55
examples/seed/src/Optics.hs Normal file
View File

@ -0,0 +1,55 @@
{-# language DataKinds #-}
{-# language DuplicateRecordFields #-}
{-# language FlexibleContexts #-}
{-# language OverloadedLabels #-}
{-# language OverloadedStrings #-}
{-# language PartialTypeSignatures #-}
{-# language TypeOperators #-}
{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
module Main where
import Control.Concurrent (threadDelay)
import Control.Monad.IO.Class (liftIO)
import Control.Monad.Logger
import Data.Conduit
import Data.Conduit.Combinators as C
import Data.Text as T
import Mu.GRpc.Server
import Mu.Schema
import Mu.Schema.Optics
import Mu.Server
import Schema
type Person = Term Maybe SeedSchema (SeedSchema :/: "Person")
type PeopleRequest = Term Maybe SeedSchema (SeedSchema :/: "PeopleRequest")
type PeopleResponse = Term Maybe SeedSchema (SeedSchema :/: "PeopleResponse")
main :: IO ()
main = do
putStrLn "running seed application"
runGRpcAppTrans 8080 runStderrLoggingT server
-- Server implementation
-- https://github.com/higherkindness/mu/blob/master/modules/examples/seed/server/modules/process/src/main/scala/example/seed/server/process/ProtoPeopleServiceHandler.scala
server :: (MonadServer m, MonadLogger m) => ServerT Maybe PeopleService m _
server = Server (getPerson :<|>: getPersonStream :<|>: H0)
evolvePerson :: PeopleRequest -> PeopleResponse
evolvePerson req = record (Just $ record (req ^. #name, Just 18))
getPerson :: Monad m => PeopleRequest -> m PeopleResponse
getPerson = pure . evolvePerson
getPersonStream :: (MonadServer m, MonadLogger m)
=> ConduitT () PeopleRequest m ()
-> ConduitT PeopleResponse Void m ()
-> m ()
getPersonStream source sink = runConduit $ source .| C.mapM reStream .| sink
where
reStream req = do
liftIO $ threadDelay (2 * 1000 * 1000) -- 2 sec
logDebugN $ T.pack $ "stream request: " ++ show req
pure $ evolvePerson req

27
examples/seed/src/Schema.hs
View File

@ -1,8 +1,5 @@
{-# language CPP #-}
{-# language DataKinds #-}
{-# language DeriveAnyClass #-}
{-# language DeriveGeneric #-}
{-# language DuplicateRecordFields #-}
{-# language FlexibleContexts #-}
{-# language FlexibleInstances #-}
{-# language MultiParamTypeClasses #-}
@ -13,34 +10,10 @@
module Schema where
import Data.Int (Int32)
import Data.Text as T
import GHC.Generics
import Mu.Quasi.GRpc
import Mu.Schema
#if __GHCIDE__
grpc "SeedSchema" id "examples/seed/seed.proto"
#else
grpc "SeedSchema" id "seed.proto"
#endif
data Person = Person
{ name :: Maybe T.Text
, age :: Maybe Int32
} deriving ( Eq, Show, Ord, Generic
, ToSchema Maybe SeedSchema "Person"
, FromSchema Maybe SeedSchema "Person" )
newtype PeopleRequest = PeopleRequest
{ name :: Maybe T.Text
} deriving ( Eq, Show, Ord, Generic
, ToSchema Maybe SeedSchema "PeopleRequest"
, FromSchema Maybe SeedSchema "PeopleRequest" )
newtype PeopleResponse = PeopleResponse
{ person :: Maybe Person
} deriving ( Eq, Show, Ord, Generic
, ToSchema Maybe SeedSchema "PeopleResponse"
, FromSchema Maybe SeedSchema "PeopleResponse" )

18
examples/with-persistent/mu-example-with-persistent.cabal
View File

@ -65,3 +65,21 @@ executable persistent-client-record
hs-source-dirs: src
default-language: Haskell2010
ghc-options: -Wall
executable persistent-client-optics
main-is: ClientOptics.hs
other-modules: Schema
build-depends: base >=4.12 && <5
, conduit
, mu-schema
, mu-rpc
, mu-persistent
, mu-protobuf
, mu-grpc-client
, persistent
, persistent-sqlite
, persistent-template
, text
hs-source-dirs: src
default-language: Haskell2010
ghc-options: -Wall

42
examples/with-persistent/src/ClientOptics.hs Normal file
View File

@ -0,0 +1,42 @@
{-# language DataKinds #-}
{-# language OverloadedLabels #-}
module Main where
import Data.Conduit
import qualified Data.Conduit.Combinators as C
import qualified Data.Text as T
import Mu.GRpc.Client.Optics
import System.Environment
import Text.Read (readMaybe)
import Schema
main :: IO ()
main = do
Right client <- initGRpc (grpcClientConfigSimple "127.0.0.1" 1234 False)
args <- getArgs
case args of
["watch"] -> watching client
["get", idp] -> get client idp
["add", nm, ag] -> add client nm ag
_ -> putStrLn "unknown command"
get :: GRpcConnection PersistentService -> String -> IO ()
get client idPerson = do
let req = readMaybe idPerson
putStrLn $ "GET: is there some person with id: " ++ idPerson ++ "?"
response <- (client ^. #getPerson) (record req)
putStrLn $ "GET: response was: " ++ show response
add :: GRpcConnection PersistentService -> String -> String -> IO ()
add client nm ag = do
let p = record (Nothing, Just (T.pack nm), readMaybe ag)
putStrLn $ "ADD: creating new person " ++ nm ++ " with age " ++ ag
response <- (client ^. #newPerson) p
putStrLn $ "ADD: was creating successful? " ++ show response
watching :: GRpcConnection PersistentService -> IO ()
watching client = do
replies <- client ^. #allPeople
runConduit $ replies .| C.mapM_ print

3
grpc/client/mu-grpc-client.cabal
View File

@ -21,6 +21,7 @@ source-repository head
library
exposed-modules: Mu.GRpc.Client.TyApps,
Mu.GRpc.Client.Record,
Mu.GRpc.Client.Optics,
Mu.GRpc.Client.Examples
other-modules: Mu.GRpc.Client.Internal
build-depends: base >=4.12 && <5
@ -31,9 +32,11 @@ library
, http2-client
, http2-client-grpc
, http2-grpc-proto3-wire
, mu-optics
, mu-protobuf
, mu-rpc
, mu-schema
, optics-core
, sop-core
, stm
, stm-chans

2
grpc/client/src/Mu/GRpc/Client/Internal.hs
View File

@ -101,7 +101,7 @@ instance ( KnownName name, FromProtoBufTypeRef rref r
rpc = RPC pkgName srvName methodName
instance ( KnownName name, FromProtoBufTypeRef rref r
, handler ~ (IO (ConduitT () (GRpcReply r) IO ())) )
, handler ~ IO (ConduitT () (GRpcReply r) IO ()) )
=> GRpcMethodCall ('Method name anns '[ ] ('RetStream rref)) handler where
gRpcMethodCall pkgName srvName _ client
= do -- Create a new TMChan

132
grpc/client/src/Mu/GRpc/Client/Optics.hs Normal file
View File

@ -0,0 +1,132 @@
{-# language AllowAmbiguousTypes #-}
{-# language DataKinds #-}
{-# language FlexibleInstances #-}
{-# language FunctionalDependencies #-}
{-# language GADTs #-}
{-# language KindSignatures #-}
{-# language RankNTypes #-}
{-# language ScopedTypeVariables #-}
{-# language TypeApplications #-}
{-# language TypeOperators #-}
{-# language UndecidableInstances #-}
{-|
Description : Client for gRPC services using optics and labels
For further information over initialization of the connection,
consult the <http://hackage.haskell.org/package/http2-client-grpc http2-client-grpc docs>.
-}
module Mu.GRpc.Client.Optics (
-- * Initialization of the gRPC client
GRpcConnection
, initGRpc
, G.GrpcClientConfig
, G.grpcClientConfigSimple
-- * Request arguments and responses
, CompressMode
, GRpcReply(..)
-- * Re-exported for convenience
, module Optics.Core
, module Mu.Schema.Optics
) where
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as BS
import Data.Conduit
import Data.Proxy
import GHC.TypeLits
import Network.GRPC.Client (CompressMode)
import qualified Network.GRPC.Client.Helpers as G
import Network.HTTP2.Client (ClientError)
import Optics.Core
import Mu.GRpc.Client.Internal
import Mu.Rpc
import Mu.Schema
import Mu.Schema.Optics
-- | Represents a connection to the service @s@.
newtype GRpcConnection (s :: Service Symbol Symbol)
= GRpcConnection { gcClient :: G.GrpcClient }
-- | Initializes a connection to a gRPC server.
-- Usually the service you are connecting to is
-- inferred from the usage later on.
-- However, it can also be made explicit by using
--
-- > initGRpc config @Service
--
initGRpc :: G.GrpcClientConfig -- ^ gRPC configuration
-> forall s. IO (Either ClientError (GRpcConnection s))
initGRpc config = do
setup <- setupGrpcClient' config
case setup of
Left e -> return $ Left e
Right c -> return $ Right $ GRpcConnection c
instance forall (serviceName :: Symbol) anns (methods :: [Method Symbol]) (m :: Symbol) (t :: *).
( SearchMethodOptic methods m t
, KnownName serviceName
, KnownName (FindPackageName anns))
=> LabelOptic m A_Getter
(GRpcConnection ('Service serviceName anns methods))
(GRpcConnection ('Service serviceName anns methods))
t t where
labelOptic = to (searchMethodOptic (Proxy @methods) (Proxy @m) pkgName svrName . gcClient)
where pkgName = BS.pack (nameVal (Proxy @(FindPackageName anns)))
svrName = BS.pack (nameVal (Proxy @serviceName))
class SearchMethodOptic (methods :: [Method Symbol]) (m :: Symbol) t
| methods m -> t where
searchMethodOptic :: Proxy methods -> Proxy m -> ByteString -> ByteString -> G.GrpcClient -> t
{- Not possible due to functional dependency
instance TypeError ('Text "could not find method " ':<>: ShowType m)
=> SearchMethodOptic '[] m t where
-}
instance {-# OVERLAPS #-} MethodOptic ('Method name anns ins outs) t
=> SearchMethodOptic ('Method name anns ins outs ': rest) name t where
searchMethodOptic _ _ pkg srv = methodOptic pkg srv (Proxy @('Method name anns ins outs))
instance {-# OVERLAPPABLE #-} SearchMethodOptic rest name t
=> SearchMethodOptic ('Method other anns ins outs ': rest) name t where
searchMethodOptic _ = searchMethodOptic (Proxy @rest)
class GRpcMethodCall method t => MethodOptic (method :: Method Symbol) t
| method -> t where
methodOptic :: ByteString -> ByteString -> Proxy method -> G.GrpcClient -> t
methodOptic = gRpcMethodCall
-- No arguments
instance forall (name :: Symbol) anns t.
( GRpcMethodCall ('Method name anns '[ ] 'RetNothing) t
, t ~ IO (GRpcReply ()) )
=> MethodOptic ('Method name anns '[ ] 'RetNothing) t
instance forall (name :: Symbol) (sch :: Schema Symbol Symbol) (r :: Symbol) anns t.
( GRpcMethodCall ('Method name anns '[ ] ('RetSingle ('ViaSchema sch r))) t
, t ~ IO (GRpcReply (Term Maybe sch (sch :/: r))) )
=> MethodOptic ('Method name anns '[ ] ('RetSingle ('ViaSchema sch r))) t
instance forall (name :: Symbol) (sch :: Schema Symbol Symbol) (r :: Symbol) anns t.
( GRpcMethodCall ('Method name anns '[ ] ('RetStream ('ViaSchema sch r))) t
, t ~ IO (ConduitT () (GRpcReply (Term Maybe sch (sch :/: r))) IO ()) )
=> MethodOptic ('Method name anns '[ ] ('RetStream ('ViaSchema sch r))) t
-- Simple arguments
instance forall (name :: Symbol) (sch :: Schema Symbol Symbol) (v :: Symbol) anns t.
( GRpcMethodCall ('Method name anns '[ 'ArgSingle ('ViaSchema sch v) ] 'RetNothing) t
, t ~ (Term Maybe sch (sch :/: v) -> IO (GRpcReply ())) )
=> MethodOptic ('Method name anns '[ 'ArgSingle ('ViaSchema sch v) ] 'RetNothing) t
instance forall (name :: Symbol) (sch :: Schema Symbol Symbol) (v :: Symbol) (r :: Symbol) anns t.
( GRpcMethodCall ('Method name anns '[ 'ArgSingle ('ViaSchema sch v) ] ('RetSingle ('ViaSchema sch r))) t
, t ~ (Term Maybe sch (sch :/: v) -> IO (GRpcReply (Term Maybe sch (sch :/: r))) ) )
=> MethodOptic ('Method name anns '[ 'ArgSingle ('ViaSchema sch v) ] ('RetSingle ('ViaSchema sch r))) t
instance forall (name :: Symbol) (sch :: Schema Symbol Symbol) (v :: Symbol) (r :: Symbol) anns t.
( GRpcMethodCall ('Method name anns '[ 'ArgSingle ('ViaSchema sch v) ] ('RetStream ('ViaSchema sch r))) t
, t ~ (Term Maybe sch (sch :/: v) -> IO (ConduitT () (GRpcReply (Term Maybe sch (sch :/: r))) IO ()) ) )
=> MethodOptic ('Method name anns '[ 'ArgSingle ('ViaSchema sch v) ] ('RetStream ('ViaSchema sch r))) t
-- Stream arguments
instance forall (name :: Symbol) (sch :: Schema Symbol Symbol) (v :: Symbol) (r :: Symbol) anns t.
( GRpcMethodCall ('Method name anns '[ 'ArgStream ('ViaSchema sch v) ] ('RetSingle ('ViaSchema sch r))) t
, t ~ (CompressMode -> IO (ConduitT (Term Maybe sch (sch :/: v)) Void IO (GRpcReply (Term Maybe sch (sch :/: r))))) )
=> MethodOptic ('Method name anns '[ 'ArgStream ('ViaSchema sch v) ] ('RetSingle ('ViaSchema sch r))) t
instance forall (name :: Symbol) (sch :: Schema Symbol Symbol) (v :: Symbol) (r :: Symbol) anns t.
( GRpcMethodCall ('Method name anns '[ 'ArgStream ('ViaSchema sch v) ] ('RetStream ('ViaSchema sch r))) t
, t ~ (CompressMode -> IO (ConduitT (Term Maybe sch (sch :/: v)) (GRpcReply (Term Maybe sch (sch :/: r))) IO ())) )
=> MethodOptic ('Method name anns '[ 'ArgStream ('ViaSchema sch v) ] ('RetStream ('ViaSchema sch r))) t

1
stack-nightly.yaml
View File

@ -4,6 +4,7 @@ allow-newer: true
packages:
- core/schema
- core/rpc
- core/optics
- adapter/avro
- adapter/protobuf
- adapter/persistent

3
stack.yaml
View File

@ -4,6 +4,7 @@ allow-newer: true
packages:
- core/schema
- core/rpc
- core/optics
- adapter/avro
- adapter/protobuf
- adapter/persistent
@ -32,3 +33,5 @@ extra-deps:
- stm-hamt-1.2.0.4
- stm-containers-1.1.0.4
- AC-Angle-1.0
- optics-core-0.2
- indexed-profunctors-0.1

7
templates/grpc-server.hsfiles
View File

@ -25,12 +25,13 @@ executable {{name}}
mu-grpc-server
{-# START_FILE stack.yaml #-}
resolver: lts-14.21
resolver: lts-14.22
allow-newer: true
extra-deps:
# mu
- mu-schema-0.1.0.0
- mu-rpc-0.1.0.0
- mu-optics-0.1.0.0
- mu-protobuf-0.1.0.0
- mu-grpc-server-0.1.0.1
- compendium-client-0.1.0.1
@ -87,12 +88,16 @@ import Mu.Schema
grpc "TheSchema" id "{{name}}.proto"
-- A. Map to Haskell types
-- data Message
-- = Message { ... }
-- deriving ( Eq, Show, Generic
-- , ToSchema Maybe TheSchema "Message"
-- , FromSchema Maybe TheSchema "Message" )
-- B. Use optics
type Message = Term Maybe TheSchema (TheSchema :/: "Message")
{-# START_FILE src/Main.hs #-}
{-# language FlexibleContexts #-}
{-# language PartialTypeSignatures #-}