Chaining Dart futures - possible to access intermediate results?

You can use a nested assignment to avoid curly braces and return :

.then((RedisClient rc) => (redisClient = rc).exists(indexKey))

You can do scopes with futures too, by not putting all the 'then' calls at the same level.I'd do something like:

Future<String> FirstValue(String indexKey) =>     RedisClient.connect(Config.connectionStringRedis)        .then((RedisClient redisClient) =>             redisClient.exists(indexKey)                 .then((bool exists) => !exists ? null : redisClient.smembers(indexKey))                 .then((Set<String> keys) => redisClient.get(keys.first))                 .then((String value) => "result: $value");         );

Indentation is always difficult with code like this. This example follows the Dart style guide, but I think it could be more readable with less indentation of the then calls:

Future<String> FirstValue(String indexKey) =>     RedisClient.connect(Config.connectionStringRedis)    .then((RedisClient redisClient) =>         redisClient.exists(indexKey)         .then((bool exists) => !exists ? null : redisClient.smembers(indexKey))         .then((Set<String> keys) => redisClient.get(keys.first))         .then((String value) => "result: $value");     );