hide some generics that don't need to be generic

src/main.rs

@@ -5,7 +5,7 @@ use anyhow::{Context, Error, Result};
 use future::ok;
 use futures::prelude::*;
 use net::{ClientMessage, ServerMessage, server::greet};
-use serde_json::{from_str, to_string, Value};
+use serde_json::{from_str, to_string};
 use std::net::ToSocketAddrs;
 use stream::FuturesUnordered;
 use structopt::StructOpt;
@@ -53,7 +53,7 @@ async fn main() -> Result<()> {
 async fn handle_socket(websocket: WebSocket) -> Result<()> {
     let (sink, mut source) = websocket.split();
 
-    let mut sink = sink.with(|msg: ServerMessage<Vec<Value>, Value>| {
+    let mut sink = sink.with(|msg: ServerMessage| {
         let json = to_string(&msg).expect("JSON encoding shouldn't fail");
         ok::<Message, Error>(Message::text(json))
     });
@@ -64,7 +64,7 @@ async fn handle_socket(websocket: WebSocket) -> Result<()> {
         match source.next().await {
             Some(Ok(msg)) => match msg.to_str() {
                 Ok(json) => {
-                    let msg = from_str::<ClientMessage<Value, Value>>(json).context("Parsing JSON")?;
+                    let msg = from_str::<ClientMessage>(json).context("Parsing JSON")?;
                     debug!("Client message: {:?}", &msg);
                 }
                 Err(()) => debug!("Non-text message"),

src/net/mod.rs

@@ -1,10 +1,11 @@
 use serde::{Deserialize, Serialize};
+use serde_json::Value;
 
 pub mod server;
 
 #[derive(Deserialize, Debug)]
 #[serde(tag = "t")]
-pub enum ClientMessage<I, S> {
+pub enum ClientMessage<I = Value, S = Value> {
     #[serde(rename = "s")]
     SetState { s: S },
     #[serde(rename = "i")]
@@ -21,7 +22,7 @@ pub struct Meta {
 
 #[derive(Serialize, Debug)]
 #[serde(tag = "t")]
-pub enum ServerMessage<I, S> {
+pub enum ServerMessage<I = Vec<Value>, S = Value> {
     #[serde(rename = "m")]
     Meta {
         #[serde(flatten)]

src/net/server.rs

@@ -1,11 +1,11 @@
 use anyhow::{Context, Error, Result};
 use super::*;
 use futures::prelude::*;
-use serde_json::{Value, json};
+use serde_json::json;
 use stream::iter;
 
 pub async fn greet<T>(sink: &mut T) -> Result<()>
-where T: Sink<ServerMessage<Vec<Value>, Value>, Error = Error> + Unpin
+where T: Sink<ServerMessage, Error = Error> + Unpin
 {
     let mut greeting = iter(vec![
         ServerMessage::Meta {