With the recent announcement of cats-effect, a relevant question from the past resurfaces: why does IO, which is otherwise quite Task-like, not define both or race? To be clear, the type signatures of these functions would be as follows:
object IO {
def both[A, B](ioa: IO[A], iob: IO[B])(implicit EC: ExecutionContext): IO[(A, B)] = ???
def race[A, B](ioa: IO[A], iob: IO[B])(implicit EC: ExecutionContext): IO[Either[A, B]] = ???
}
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A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.
val square : Int => Int = x => x * x
Every application ever written can be viewed as some sort of transformation on data. Data can come from different sources, such as a network or a file or user input or the Large Hadron Collider. It can come from many sources all at once to be merged and aggregated in interesting ways, and it can be produced into many different output sinks, such as a network or files or graphical user interfaces. You might produce your output all at once, as a big data dump at the end of the world (right before your program shuts down), or you might produce it more incrementally. Every application fits into this model.
The scalaz-stream project is an attempt to make it easy to construct, test and scale programs that fit within this model (which is to say, everything). It does this by providing an abstraction around a "stream" of data, which is really just this notion of some number of data being sequentially pulled out of some unspecified data source. On top of this abstraction, sca
(by @andrestaltz)
If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.
| package com.example.anothersignintest; | |
| import com.google.android.gms.auth.api.Auth; | |
| import com.google.android.gms.auth.api.signin.GoogleSignInAccount; | |
| import com.google.android.gms.auth.api.signin.GoogleSignInOptions; | |
| import com.google.android.gms.auth.api.signin.GoogleSignInResult; | |
| import com.google.android.gms.common.ConnectionResult; | |
| import com.google.android.gms.common.api.GoogleApiClient; | |
| import com.google.android.gms.common.api.OptionalPendingResult; | |
| import com.google.android.gms.common.api.ResultCallback; |
Locate the section for your github remote in the .git/config file. It looks like this:
[remote "origin"]
fetch = +refs/heads/*:refs/remotes/origin/*
url = [email protected]:joyent/node.git
Now add the line fetch = +refs/pull/*/head:refs/remotes/origin/pr/* to this section. Obviously, change the github url to match your project's URL. It ends up looking like this:
| git fetch upstream | |
| git reset --hard upstream/master |