Igor

Igor is a dialect of Go language with the support for structured concurrency.

WARNING: This project is meant as a playground for experimenting with what a language with native support fot structured concurrency would look like. If you want to do serious work, please use golang.org/x/sync/errgroup instead.

How does it differ from the standard go?

go statement is prohibited - very much like goto in most modern languages.

Instead, launch the goroutines in nurseries using run function:

n := make(nursery)
run(n, foo(a, b, c))
err := n.Wait()

Note that Igor uses a calling convention that differs from the standard Go. Namely, there's an implicit first context.Context argument passed to each function. Therefore, you have to call the functions from the native packages with gocc specifier:

fmt.Println.gocc("Hi there!")

Nurseries in detail

Nursery holds a set of goroutines. The goroutine function MUST must have an error return type. If goroutine exits with nil it is silently removed from the nursery. If goroutine exits with an error, all the other goroutines in the nursery are immediately canceled. The error is stored to be later returned to the owner of the nursery.

The owner, in addition to launching goroutines, can use the following functions on the nursery:

Close() immediately cancels all the goroutines in the nursery. There's no return value.

Wait() error waits until all the goroutines in the nursery are finished. If one of them fails, the error is returned from the Wait function. If no goroutine has failed, nil is returned.

Err() error checks whether the nursery failed, but doesn't block. In case of previous failure, it returns the error. If the nursery is in running state it returns nil. This function can be used when periodic checking of the health of the nursery is desired.

How does it work?

igor tool is a transpiler that takes files with extension .igor and produces standard Go files with extension .go.

To install the transpiler:

go install github.com/sustrik/igor/igor

Run it like this:

igor

The transpiler compiles all the Igor files in the current directory and in all of its subdirectories, recursively. Alternatively, starting directory can be specified on the command line:

igor ./go/src/github.com/foo/bar

The compiled Igor programs are linked with the lib/igor package which contains the language runtime.