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.cargo | ||
ast | ||
compiler | ||
examples | ||
leo | ||
types | ||
.gitignore | ||
Cargo.lock | ||
Cargo.toml | ||
Leo.toml | ||
README.md |
The Leo Programming Language
- Programs should be formatted:
- Import definitions
- Circuit definitions
- Function definitions
Mutability
- All defined variables in Leo are immutable by default.
- Variables can be made mutable with the
mut
keyword.
function main() {
let a = 0u32;
//a = 1 <- Will fail
let mut b = 0u32;
b = 1; // <- Ok
}
Booleans
Explicit types are optional.
function main() -> bool {
let a: bool = true || false;
let b = false && false;
let c = 1u32 == 1u32;
return a
}
Numbers
- The definition of a number must include an explict type.
- After assignment, you can choose to explicitly add the type or let the compiler interpret implicitly.
- Type casting is not supported.
- Comparators are not supported.
Integers
Supported integer types: u8
, u16
, u32
, u64
, u128
function main() -> u32 {
let a = 2u32; // explicit type
let a: u32 = 1 + 1; // explicit type
let b = a - 1; // implicit type
let c = b * 4;
let d = c / 2;
let e = d ** 3;
return e
}
Field Elements
function main() -> field {
let a = 1000field; // explicit type
let a: field = 21888242871839275222246405745257275088548364400416034343698204186575808495617; // explicit type
let b = a + 1; // implicit type
let c = b - 1;
let d = c * 4;
let e = d / 2;
return e
}
Affine Points
The set of affine points on the elliptic curve passed into the leo compiler forms a group. Leo supports this set as a primitive data type.
function main() -> group {
let a = 1000group; // explicit type
let a = (21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617)group; // explicit type
let b = a + 0; // implicit type
let c = b - 0;
return c
}
Operator Assignment Statements
function main() -> u32 {
let mut a = 10;
a += 5;
a -= 10;
a *= 5;
a /= 5;
a **= 2;
return a
}
Arrays
Leo supports static arrays with fixed length.
function main() -> u32[2] {
// initialize an integer array with integer values
let mut a: u32[3] = [1, 2, 3];
// set a mutable member to a value
a[2] = 4;
// initialize an array of 4 values all equal to 42
let b = [42u8; 4];
// initialize an array of 5 values copying all elements of b using a spread
let c = [1, ...b];
// initialize an array copying a slice from `c`
let d = c[1..3];
// initialize a field array
let e = [5field; 2];
// initialize a boolean array
let f = [true, false || true, true];
return d
}
Multidimensional Arrays
function main() -> u32[3][2] {
let m = [[0u32, 0u32], [0u32, 0u32]];
let m: u32[3][2] = [[0; 3]; 2];
return m
}
Conditionals
If Else Ternary Expression
function main() -> u32 {
let y = if 3==3 ? 1 : 5;
return y
}
If Else Conditional Statement
** Experimental ** The current constraint system is not optimized for statement branching. Please use the ternary expression above until this feature is stable.
function main(a: private bool, b: private bool) -> u32 {
let mut res = 0u32;
if (a) {
res = 1;
} else if (b) {
res = 2;
} else {
res = 3;
}
return res
}
For loop
function main() -> fe {
let mut a = 1field;
for i in 0..4 {
a = a + 1;
}
return a
}
Functions
function test1(a : u32) -> u32 {
return a + 1
}
function test2(b: fe) -> field {
return b * 2field
}
function test3(c: bool) -> bool {
return c && true
}
function main() -> u32 {
return test1(5)
}
Function Scope
function foo() -> field {
// return myGlobal <- not allowed
return 42field
}
function main() -> field {
let myGlobal = 42field;
return foo()
}
Multiple returns
Functions can return tuples whose types are specified in the function signature.
function test() -> (u32, u32[2]) {
return 1, [2, 3]
}
function main() -> u32[3] {
let (a, b) = test();
// (a, u32[2] b) = test() <- explicit type also works
return [a, ...b]
}
Main function inputs
Main function inputs are allocated as public or private variables in the program's constaint system.
function main(a: private field) -> field {
return a
}
function main(a: public field) -> field {
return a
}
Private by default. Below a
is implicitly private.
function main(a: field) -> field {
return a
}
Function inputs are passed by value.
function test(mut a: u32) {
a = 0;
}
function main() -> u32 {
let a = 1;
test(a);
return a // <- returns 1
}
Circuits
Circuits in Leo are similar to classes in object oriented langauges. Circuits are defined above functions in a Leo program. Circuits can have one or more members.
Members can be defined as fields which hold primitive values
circuit Point {
x: u32
y: u32
}
function main() -> u32 {
let p = Point {x: 1, y: 0};
return p.x
}
Members can also be defined as functions.
circuit Circ {
function echo(x: u32) -> u32 {
return x
}
}
function main() -> u32 {
let c = Circ { };
return c.echo(1u32)
}
Circuit functions can be made static, enabling them to be called without instantiation.
circuit Circ {
static function echo(x: u32) -> u32 {
return x
}
}
function main() -> u32 {
return Circ::echo(1u32)
}
The Self
keyword is supported in circuit functions.
circuit Circ {
b: bool
static function new() -> Self {
return Self { b: true }
}
}
function main() -> Circ {
let c = Circ::new();
return c.b
}
Imports
Both struct and function imports are supported.
import all: *
import alias: symbol as alias
src/simple_import.leo
circuit Point {
x: u32
y: u32
}
function test() -> (u32, u32[2]) {
return 1, [2, 3]
}
src/simple.leo
from "./simple_import" import {
Point as Foo,
test
};
// from "./simple_import" import *
function main() -> (u32[3]) {
let p = Foo { x: 1, y: 2};
let (a, b) = test();
return [a, ...b]
}
Constraints
Assert Equals
This will enforce that the two values are equal in the constraint system.
function main() {
assert_eq(45, 45);
assert_eq(2fe, 2fe);
assert_eq(true, true);
}
Testing
Use the test
keyword to add tests to a leo program. Tests must have 0 function inputs and 0 function returns.
function main(a: u32) -> u32 {
return a
}
test function expect_pass() {
let a = 1u32;
let res = main(a);
assert_eq!(res, 1u32);
}
test function expect_fail() {
assert_eq!(1u8, 0u8);
}
Leo CLI
Develop
leo new
To setup a new package, run:
leo new {$NAME}
This will create a new directory with a given package name. The new package will have a directory structure as follows:
- inputs # Your program inputs
- outputs # Your program outputs
- src
- lib.leo # Your program library
- main.leo # Your program
- tests
- test.leo # Your program tests
- Leo.toml # Your program manifest
leo init
To initialize an existing directory, run:
leo init
This will initialize the current directory with the same package directory setup.
leo build
To compile your program and verify that it builds properly, run:
leo build
leo test
To execute unit tests on your program, run:
leo test
The results of test compilation and the constraint system will be printed:
INFO leo Running 2 tests
INFO leo test language::expect_pass compiled. Constraint system satisfied: true
ERROR leo test language::expect_fail errored: Assertion 1u8 == 0u8 failed
Run
leo setup
To perform the program setup, producing a proving key and verification key, run:
leo setup
Leo uses cryptographic randomness from your machine to perform the setup. The proving key and verification key are stored in the target
directory as .leo.pk
and .leo.vk
:
{$LIBRARY}/target/{$PROGRAM}.leo.pk
{$LIBRARY}/target/{$PROGRAM}.leo.vk
leo prove
To execute the program and produce an execution proof, run:
leo prove
Leo starts by checking the target
directory for an existing .leo.pk
file. If it doesn't exist, it will proceed to run leo setup
and then continue.
Once again, Leo uses cryptographic randomness from your machine to produce the proof. The proof is stored in the target
directory as .leo.proof
:
{$LIBRARY}/target/{$PROGRAM}.leo.proof
leo verify
To verify the program proof, run:
leo verify
Leo starts by checking the target
directory for an existing .leo.proof
file. If it doesn't exist, it will proceed to run leo prove
and then continue.
After the verifier is run, Leo will output either true
or false
based on the verification.
Remote
To use remote compilation features, start by authentication with:
leo login
You will proceed to authenticate using your username and password. Next, Leo will parse your Leo.toml
file for remote = True
to confirm whether remote compilation is enabled.
If remote compilation is enabled, Leo syncs your workspace so when you run leo build
, leo test
, leo setup
and leo prove
, your program will run the program setup and execution performantly on remote machines.
This speeds up the testing cycle and helps the developer to iterate significantly faster.
Publish
To package your program as a gadget and publish it online, run:
leo publish
Leo will proceed to snapshot your directory and upload your directory to the circuit manager. Leo will verify that leo build
succeeds and that leo test
passes without error.
If your gadget name has already been taken, leo publish
will fail.
Deploy
To deploy your program to Aleo, run:
leo deploy
Install
To install Leo from source, in the root directory of the repository, run:
cargo install --path .
TODO
- Change
target
directory to some other directory to avoid collision. - Figure out how
leo prove
should take in assignments. - Come up with a serialization format for
.leo.pk
,.leo.vk
, and.leo.proof
.