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Improved Go (igo) GoDoc

Everyone knows that Go is a very verbose language. It takes numerous lines of code to do what a few lines of code can do in other languages. This is a deliberate design decision by the Go Authors.

The igo project provides various syntactical sugar to make your code simpler and easier to read. It works by allowing you to program in *.igo files with the fancy new syntax. You then run igo build to transpile your igo files to standard go files which you can then build as per normal.

  1. Address Operator (&)
    • Constants and Functions
  2. Defers for for-loops
    • fordefer guarantees to run prior to the loop's current iteration exiting.
  3. Defer go
    • Run defer statements in a goroutine
  4. must function
    • Converts a multi-return value function into a single-return function.
    • See #32219
  5. Negative slice indices

NOTE: igo is pronounced ee-gohr

⭐ the project to show your appreciation.

What is included

  • igofmt (auto format code)
  • igo transpiler (generate standard go code)

Installation

Transpiler

go get -u github.com/rocketlaunchr/igo

Use go install to install the executable.

Formatter

go get -u github.com/rocketlaunchr/igo/igofmt

Inspiration

Most professional front-end developers are fed up with standard JavaScript. They program using Typescript and then transpile the code to standard ES5 JavaScript. igo adds the same step to the build process.

Examples

Address Operator

The Address Operator allows you to use more visually pleasing syntax. There is no need for a temporary variable. It can be used with string, bool, int, float64 and function calls where the function returns 1 return value.

func main() {

	message := &"igo is so convenient"
	display(message)

	display(&`inline string`)

	display(&defaultMessage())

}

func display(m *string) {
	if m == nil {
		fmt.Print("no message")
	} else {
		fmt.Print(*m)
	}

}

func defaultMessage() string {
	return "default message"
}

Fordefer

See Blog post on why this is an improvement. It can be especially helpful in unit tests.

for {
	row, err := db.Query("SELECT ...")
	if err != nil {
		panic(err)
	}

	fordefer row.Close()
}

Defer go

This feature makes Go's language syntax more internally consistent. There is no reason why defer and go should not work together.

mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
	start := time.Now()
	// Transmit how long the request took to serve without delaying response to client.
	defer go transmitRequestStats(start)

	fmt.Fprintf(w, "Welcome to the home page!")
})

Must builtin function

must is a "builtin" function that converts a multi-return value function ("fn") into a single-return value function. fn's final return value is expected to be of type error. must will panic upon fn returning an error.

It is useful in scenarios where you know that no error will actually be returned by fn and you just want to use the function inline. Alternatively, you may want to catch the error during local development because no error should be produced in production.

must also accepts an optional second argument of type func(error) error.

See #32219

import "database/sql"

db := must(sql.Open("mysql", "host"))

LIMITATIONS

  • Currently, it only works when fn returns two return values.
  • It doesn't work when used outside of functions (i.e. initializing package variables).
  • It works perfectly in simple cases. For more complex cases, peruse the generated code.
  • A PR would be appreciated by an expert in the go/types package. It is possible to create a truly generics-compatible must that resolves the limitations above.
  • Unlike real "builtin" functions, must is a reserved keyword.

Negative slice indices

You can use negative indices to refer to items in a slice starting from the back. It only works with constants and not variables.

x := []int{0, 1, 2, 3, 4}

x[-3] // x[len(x)-3]

x[-3:-1] // x[len(x)-3:len(x)-1]

How to use

Transpile

igo can accept numerous directories or igo files. The generated go files are saved alongside the igo files.

igo build [igo files...]

Format Code

igofmt will format your code to the standard form. It understands igo syntax.

igofmt [-s] [igo files...]

Configure your IDE to run igofmt upon saving a *.igo file. -s will attempt to simplify the code by running gofmt -s.

Design Decisions and Limitations

Pull-Requests are requested for the below deficiencies.

  • For fordefer: goto statements inside a for-loop that jump outside the for-loop is not implemented. Use github.com/rocketlaunchr/igo/stack package manually in such cases.
  • goimports equivalent has not been made.
  • Address Operator for constants currently only supports string, bool, float64 and int. The other int types are not supported. This can be fixed by using go/types package.
  • Address Operator feature assumes you have not attempted to redefine true and false to something/anything else.

Tips & Advice

  • Store the igo and generated go files in your git repository.
  • Configure your IDE to run igofmt upon saving a *.igo file.

Legal Information

The license is a modified MIT license. Refer to the LICENSE file for more details.

© 2018-20 PJ Engineering and Business Solutions Pty. Ltd.

Final Notes

Feel free to enhance features by issuing pull-requests.