GoPlus - The Go+ language for data science

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}
reversedMap := {v: k for k, v <- mapData}
println(reversedMap) // 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 (not including cgo) will be supported.

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 Dive into Go+.

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/qiniu/goplus/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 ./...

Or:

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

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

Note: The gop command isn't provided currently (in alpha stage). Instead, we provide qrun and qgo commands.

Playground

Playground based on Docker:

https://play.goplus.org/

Playground based on GopherJS:

https://qiniu.github.io/goplus-play/

Tutorials

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

How to build

Current version:

go get github.com/qiniu/goplus@vX.X.XX
#or: git clone git@github.com:qiniu/goplus.git
cd goplus
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.

Commands

gop go [-test] <gopSrcDir> # Convert all Go+ packages under <gopSrcDir> into Go packages, recursively
gop run <gopSrcDir> # Running <gopSrcDir> as a Go+ main package
gop run <gopSrcFile> # Running <gopSrcFile> as a Go+ script
gop install ./... # Convert all Go+ packages under ./ and go install ./...
gop fmt ./... # Format all Go+ packages under ./
gop export <goPkgPath> # Generate a Go+ package that wraps a Go package automatically

The gop command isn't provided currently (in alpha stage). Instead, we provide the following commands:

qrun: Similar to gop run
qfmt: Similar to gop fmt
qexp: Similar to gop export
qgo: Similar to gop go

Note:

qgo -test <gopSrcDir> converts Go+ packages into Go packages, and for every package, it call go run <gopPkgDir>/gop_autogen.go and qrun -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/Map 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}

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.

Unix shebang

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

#!/usr/bin/env qrun

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