CODEWITHSUNDEEP
f#
Bård
Bård

Reputation: 634

Is there a better way to cast a return value inside an async block in F#

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?

Upvotes: 0

Views: 245

Answers (1)

Vandroiy
Vandroiy

Reputation: 6223

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.

Upvotes: 2

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