GoPlus - The Go+ language for data science

NOTE: Go+ is still under heavy developement. Please don't use it in production environment.

Summary about Go+

What are mainly impressions about Go+?

• A static typed language.
• Fully compatible with the Go language.
• Script-like style, and more readable code for data science than Go.

For example, the following is legal Go+ source code:

a := [1, 2, 3.4]
println(a)

How do we do this in the Go language?

package main

func main() {
    a := []float64{1, 2, 3.4}
    println(a)
}

Of course, we don't only do less-typing things.

For example, we support list comprehension, which makes data processing easier.

a := [1, 3, 5, 7, 11]
b := [x*x for x <- a, x > 3]
println(b) // output: [25 49 121]

mapData := {"Hi": 1, "Hello": 2, "Go+": 3}
reverseMap := {v: k for k, v <- mapData}
println(reverseMap) // output: map[1:Hi 2:Hello 3:Go+]

We will keep Go+ simple. This is why we call it Go+, not Go++.

Less is exponentially more.

It's for Go, and it's also for Go+.

Compatibility with Go

All Go features will be supported (including partially support cgo, see below).

• See supported the Go language features.

All Go packages (even these packages use cgo) can be imported by Go+.

import (
    "fmt"
    "strings"
)

x := strings.NewReplacer("?", "!").Replace("hello, world???")
fmt.Println("x:", x)

Be interested in how it works? See Import Go packages in Go+ programs.

Also, all Go+ packages can be converted into Go packages and imported in Go programs.

First, let's make a directory named tutorial/14-Using-goplus-in-Go.

Then write a Go+ package named foo in it:

package foo

func ReverseMap(m map[string]int) map[int]string {
    return {v: k for k, v <- m}
}

Then use it in a Go package:

package main

import (
	"fmt"

	"github.com/goplus/gop/tutorial/14-Using-goplus-in-Go/foo"
)

func main() {
	rmap := foo.ReverseMap(map[string]int{"Hi": 1, "Hello": 2})
	fmt.Println(rmap)
}

How to compile this example?

gop go tutorial/ # Convert all Go+ packages in tutorial/ into Go packages
go install ./...

gop install ./... # Convert Go+ packages and go install ./...

Go tutorial/14-Using-goplus-in-Go to get the source code.

Playground/REPL

Go+ REPL based on GopherJS/WASM:

• https://repl.goplus.org/

Go+ Playground based on Docker:

• https://play.goplus.org/

Go+ Playground based on GopherJS:

• https://goplusjs.github.io/play/

Go+ Jupyter kernel:

• https://github.com/wangfenjin/gopyter

Tutorials

See https://github.com/goplus/gop/tree/master/tutorial

How to build

git clone [email protected]:goplus/gop.git
cd gop
go install -v ./...

Go+ features

Bytecode vs. Go code

Go+ supports bytecode backend and Go code generation.

When we use gop go or gop install command, it generates Go code to covert Go+ package into Go packages.

When we use gop run command, it doesn't call go run command. It generates bytecode to execute.

In bytecode mode, Go+ doesn't support cgo. However, in Go-code-generation mode, Go+ fully supports cgo.

Commands

gop run         # Run a Go+ program
gop repl        # Run Go+ in REPL/Console mode
gop go [-test]  # Convert Go+ packages into Go packages. If -test specified, it tests related packages.
gop fmt         # Format Go+ packages
gop export      # Export Go packages for Go+ programs

See https://github.com/goplus/gop/wiki/Commands for details.

Note:

• gop go -test <gopSrcDir> converts Go+ packages into Go packages, and for every package, it call go run <gopPkgDir>/gop_autogen.go and gop run -quiet <gopPkgDir> to compare their outputs. If their outputs aren't equal, the test case fails.

Rational number: bigint, bigrat, bigfloat

We introduce the rational number as native Go+ types. We use suffix r to denote rational literals. For example, (1r << 200) means a big int whose value is equal to 2200. And 4/5r means the rational constant 4/5.

a := 1r << 65   // bigint, large than int64
b := 4/5r       // bigrat
c := b - 1/3r + 3 * 1/2r
println(a, b, c)

Map literal

x := {"Hello": 1, "xsw": 3.4} // map[string]float64
y := {"Hello": 1, "xsw": "Go+"} // map[string]interface{}
z := {"Hello": 1, "xsw": 3} // map[string]int
empty := {} // map[string]interface{}

Slice literal

x := [1, 3.4] // []float64
y := [1] // []int
z := [1+2i, "xsw"] // []interface{}
a := [1, 3.4, 3+4i] // []complex128
b := [5+6i] // []complex128
c := ["xsw", 3] // []interface{}
empty := [] // []interface{}

List comprehension

a := [x*x for x <- [1, 3, 5, 7, 11]]
b := [x*x for x <- [1, 3, 5, 7, 11], x > 3]
c := [i+v for i, v <- [1, 3, 5, 7, 11], i%2 == 1]
d := [k+","+s for k, s <- {"Hello": "xsw", "Hi": "Go+"}]

arr := [1, 2, 3, 4, 5, 6]
e := [[a, b] for a <- arr, a < b for b <- arr, b > 2]

x := {x: i for i, x <- [1, 3, 5, 7, 11]}
y := {x: i for i, x <- [1, 3, 5, 7, 11], i%2 == 1}
z := {v: k for k, v <- {1: "Hello", 3: "Hi", 5: "xsw", 7: "Go+"}, k > 3}

Select data from a collection

type student struct {
    name  string
    score int
}

students := [student{"Ken", 90}, student{"Jason", 80}, student{"Lily", 85}]

unknownScore, ok := {x.score for x <- students, x.name == "Unknown"}
jasonScore := {x.score for x <- students, x.name == "Jason"}

println(unknownScore, ok) // output: 0 false
println(jasonScore) // output: 80

For loop

sum := 0
for x <- [1, 3, 5, 7, 11, 13, 17], x > 3 {
    sum += x
}

Error handling

We reinvent the error handling specification in Go+. We call them ErrWrap expressions:

expr! // panic if err
expr? // return if err
expr?:defval // use defval if err

How to use them? Here is an example:

import (
	"strconv"
)

func add(x, y string) (int, error) {
	return strconv.Atoi(x)? + strconv.Atoi(y)?, nil
}

func addSafe(x, y string) int {
	return strconv.Atoi(x)?:0 + strconv.Atoi(y)?:0
}

println(`add("100", "23"):`, add("100", "23")!)

sum, err := add("10", "abc")
println(`add("10", "abc"):`, sum, err)

println(`addSafe("10", "abc"):`, addSafe("10", "abc"))

The output of this example is:

add("100", "23"): 123
add("10", "abc"): 0 strconv.Atoi: parsing "abc": invalid syntax

===> errors stack:
main.add("10", "abc")
	/Users/xsw/goplus/tutorial/15-ErrWrap/err_wrap.gop:6 strconv.Atoi(y)?

addSafe("10", "abc"): 10

Compared to corresponding Go code, It is clear and more readable.

And the most interesting thing is, the return error contains the full error stack. When we got an error, it is very easy to position what the root cause is.

How these ErrWrap expressions work? See Error Handling for more information.

Auto property

Let's see an example written in Go+:

import "github.com/goplus/gop/ast/goptest"

doc := goptest.New(`... Go+ code ...`)!

println(doc.Any().FuncDecl().Name())

In many languages, there is a concept named property who has get and set methods.

Suppose we have get property, the above example will be:

import "github.com/goplus/gop/ast/goptest"

doc := goptest.New(`... Go+ code ...`)!

println(doc.any.funcDecl.name)

In Go+, we introduce a concept named auto property. It is a get property, but is implemented automatically. If we have a method named Bar(), then we will have a get property named bar at the same time.

Unix shebang

You can use Go+ programs as shell scripts now. For example:

#!/usr/bin/env -S gop run

println("Hello, Go+")

println(1r << 129)
println(1/3r + 2/7r*2)

arr := [1, 3, 5, 7, 11, 13, 17, 19]
println(arr)
println([x*x for x <- arr, x > 3])

m := {"Hi": 1, "Go+": 2}
println(m)
println({v: k for k, v <- m})
println([k for k, _ <- m])
println([v for v <- m])

Go tutorial/20-Unix-Shebang/shebang to get the source code.

Go features

All Go features (not including cgo) will be supported.

• See supported the Go language features.

IDE Plugins

• vscode: https://github.com/gopcode/vscode-goplus

Contributing

The Go+ project welcomes all contributors. We appreciate your help!

Here are list of Go+ Contributors. We award an email account ([email protected]) for every contributor. And we suggest you commit code by using this email account:

git config --global user.email [email protected]

If you did this, remember to add your [email protected] email to https://github.com/settings/emails.

What does a contributor to Go+ mean? He must meet one of the following conditions:

• At least one pull request of a full-featured implemention.
• At least three pull requests of feature enhancements.
• At least ten pull requests of any kind issues.

Where can you start?