I'm using StackExchange.Redis inside a small F# project and I need to cast the db.StringGetAsync() return value to an int. I've found a way to do it like this:
let! intFromRedis= async {
let! value = db.StringGetAsync(key) |> Async.AwaitTask
return int value
}
But it would be prettier to be able to do something like this instead:
// Better syntax but it does not compile
let! intFromRedis : int = db.StringGetAsync(key) |> Async.AwaitTask
Is there a better syntax for this?
As has been pointed out in the comments, technically, the question asks for Async.map, which could be defined similar to the code in the question.
But I'd rather recommend to keep it simple. Casting on a second line would look like this:
let! redisValue = db.StringGetAsync(key) |> Async.AwaitTask
let intFromRedis = int redisValue
And I'm not even sure intFromRedis is more readable than int redisValue. It's barely shorter, and the latter expression is self-explanatory. Thus, there's no real problem in keeping just the first line and using int redisValue.
Using rare or custom functions reduces readability. A cast – and maybe a value binding – are simple, short enough, and any programmer reading the code should understand what is happening.
Async.map is overkill.
|> intat the end?Async.mapTomas Petricek describes here: stackoverflow.com/a/6793961/126014Async.mapjust to maybe save one line of code.