tau

README

τ

Tau is a dynamically-typed open source programming language designed to be minimal, fast and efficient.

Installation

In order to install Tau, you'll need Go.

Once done, running the following command will successfully install the tau interpreter:

go install github.com/NicoNex/tau@latest

You can try it out in the terminal by simply running $ tau, alternatively to take advantage of the builtin virtual machine and gain a lot of performance run it with $ tau -vm. The flag -vm works when executing files too. For additional info run $ tau --help.

Syntax

Hello World

We all start from here...

println("Hello World")

Examples

File

As every interpreter Tau supports files either by passing the path to the interpreter or by using the shebang.

#!/path/to/tau

println("hello world")

$ tau helloworld.tau
hello world

if-else blocks

if 1 > 0 {
	println("yes")
} else {
	println("no")
}

myVar = 10

if myVar > 10 {
	println("more than 10")
} else if myVar == 10 {
	println("it's exactly 10")
} else {
	println(myVar)
}

Declaring a function

loop = fn(times, function) {
	if times > 0 {
		function()
		loop(times-1, function)
	}
}

loop(5, fn() { println("Hello World") })

Noteworthy features

The return value can be implicit:

add = fn(x, y) { x + y }
sum = add(9, 1)
println(sum)

>>> 10

Also you can inline the if expressions:

a = 0
b = 1

minimum = if a < b { a } else { b }

The semicolon character ; is implicit on a newline but can be used to separate multiple expressions on a single line.

printData = fn(a, b, c) { println(a); println(b); println(c) }

Functions are first-class and treated as any other data type.

min = fn(a, b) {
	if a < b {
		return a
	}
	b
}

var1 = 1
var2 = 2

m = min(var1, var2)
println(m)

>>> 1

Error handling

# errtest.tau

div = fn(n, d) {
	if d == 0 {
		return error("zero division error")
	}
	n / d
}

if failed(result1 = div(16, 2)) {
	exit(result1)
}
println("the result of 16 / 2 is", result1)

if failed(result2 = div(32, 0)) {
	exit(result2)
}
println("the result of 32 / 0 is", result2)

$ tau errtest.tau
the result of 16 / 2 is 8
error: zero division error
$

REPL

Tau also supports REPL:

>>> add = fn(a, b) { a + b }
>>> string(add)
fn(a, b) { (a + b) }
>>> string(21)
21
>>> recursive_loop = fn(n, func) { if n != 0 { func(n); recursive_loop(n-1, func) } }
>>> recursive_loop(10, fn(n) { println("hello", n) })
hello 10
hello 9
hello 8
hello 7
hello 6
hello 5
hello 4
hello 3
hello 2
hello 1

Data types

Tau is a dynamically-typed programming language and it supports the following primitive types:

Integer

my_var = 10

Float

my_var = 2.5

String

str = "My string here"

Boolean

t = true
f = false

Function

pow = fn(base, exponent) {
	if exponent > 0 {
		return base * pow(base, exponent-1)
	}
	1 # You could optionally write 'return 1', but in this case the return is implicit.
}

List

empty = []
stuff = ["Hello World", 1, 2, 3, true]

Map

empty = {}
stuff = {"Hello": "World", 123: true}

Loop

for i = 0; i < 10; ++i {
	println("hello world", i)
}

lst = [0, 1, 2, 3, 4]

println(lst)
for len(lst) > 0 {
	println(lst = tail(lst))
}

Objects

obj = new()
obj.value1 = 123
obj.value2 = 456

obj.sum_values = fn() {
	obj.value1 + obj.value2
}

obj.child = new()
obj.child.value = obj.sum_values()

Recommended usage

Dog = fn(name, age) {
	dog = new()

	dog.name = name
	dog.age = age

	dog.humanage = fn() {
		dog.age * 7
	}

	return dog
}

snuffles = Dog("Snuffles", 8)
println(snuffles.humanage())

>>> 56

Modules

Plugin

Tau plugin system makes it possible to import and use Go plugins in Tau seamlessly. To run your Go code in Tau just compile it with:

go build -buildmode=plugin -o myplugin.so

then you can import it in Tau with the plugin builtin function.

myplugin = plugin("path/to/myplugin.so")

Example

Go code:

package main

import "fmt"

func Hello() {
	fmt.Println("Hello World")
}

func Sum(a, b int) int {
	return a + b
}

Tau code:

myplugin = plugin("myplugin.so")

myplugin.Hello()
println("The sum is", myplugin.Sum(3, 2))

Output:

>>> Hello World
>>> The sum is 5

Documentation

Index

• Variables
• func CompileFiles(files []string) error
• func EvalREPL() error
• func ExecFileEval(f string) error
• func ExecFileVM(f string) error
• func VmREPL() error

Variables

var (
	ErrParseError = errors.New("error: parse error")
)

Functions

func CompileFiles

func CompileFiles(files []string) error

func EvalREPL

func EvalREPL() error

func ExecFileEval

func ExecFileEval(f string) error

func ExecFileVM

func ExecFileVM(f string) error

func VmREPL

func VmREPL() error