Syntax and Examples

This page provides a comprehensive guide to StoffelLang syntax, featuring practical examples and detailed explanations of the language’s features.

Basic Elements

Comments

StoffelLang uses # for comments:

# This is a single-line comment
var x = 42  # Inline comment

# Multi-line comments can be created
# by using multiple single-line comments

Identifiers and Keywords

Valid identifiers:

Must start with a letter or underscore
Can contain letters, numbers, and underscores
Case-sensitive

var my_variable = 10
var _private_value = "secret"
var camelCase = true
var snake_case_name = "Alice"

Reserved keywords:

var def type object enum main
if else elif while for in
return break continue
true false nil secret discard

Variables and Types

Variable Declarations

StoffelLang uses var for variable declarations:

# Variable with type inference
var name = "Alice"
var age = 25
var is_active = true

# Variable with explicit type annotation
var counter: int64 = 0
var status: string = "pending"

# Variable declaration without initialization (requires type)
var result: int64

Type Annotations

Explicit type annotations use colon syntax:

var count: int64 = 100
var message: string = "Hello"
var flag: bool = false

Type Inference

StoffelLang can infer types from context:

var inferred_int = 42        # int64
var inferred_string = "text" # string
var inferred_bool = true     # bool

Primitive Types

Integer Types

StoffelLang supports multiple integer types:

# Signed integers
var a: int64 = 100
var b: int32 = 50
var c: int16 = 25
var d: int8 = 10

# Unsigned integers
var e: uint64 = 100
var f: uint32 = 50
var g: uint16 = 25
var h: uint8 = 10

# Typed integer literals
var typed_i64 = 42i64
var typed_u32 = 100u32
var typed_i8 = 127i8

Boolean Type

var is_ready: bool = true
var is_complete: bool = false

String Type

var greeting: string = "Hello, world!"
var empty_string: string = ""

Nil Type

var nothing = nil

Secret Types

The secret keyword creates MPC-aware types for secure computation:

# Secret variable declaration
secret var my_secret = 42

# Secret with explicit type
var secret_value: secret int64 = 100

# Secret function parameter
def process_secret(data: secret int64) -> secret int64:
    return data * 2

Important Constraints:

Secret values cannot be used in if or while conditions
Comparisons involving secrets produce secret boolean results
Use ClientStore.take_share() to get secret inputs from MPC clients

Functions

Function Definitions

Functions use the def keyword:

# Basic function
def greet(name: string) -> string:
    return "Hello, " + name

# Function with multiple parameters
def add(a: int64, b: int64) -> int64:
    return a + b

# Function without return value
def log_message(msg: string) -> nil:
    print(msg)

# Function with secret parameters
def secure_multiply(a: secret int64, b: secret int64) -> secret int64:
    return a * b

Entry Point

The program entry point uses the main keyword:

main main() -> int64:
    return 42

Function Calls

# Basic function calls
var result = add(10, 20)
var greeting = greet("Alice")

# Nested function calls
var complex_result = add(add(1, 2), add(3, 4))

Functions with Local Variables

def calculate_area(length: int64, width: int64) -> int64:
    var area = length * width
    print("Area calculated")
    return area

Control Flow

If Statements

# Basic if statement
if age >= 18:
    print("Adult")

# If-else
if temperature > 30:
    print("Hot")
else:
    print("Not hot")

# If-elif-else
if score >= 90:
    print("A grade")
elif score >= 80:
    print("B grade")
elif score >= 70:
    print("C grade")
else:
    print("Below C grade")

While Loops

# Basic while loop
var count = 0
while count < 10:
    print("Counting")
    count = count + 1

For Loops

# Range-based for loops (inclusive)
for i in 0..10:
    print("Number")

Loop Control

# Break and continue
var i = 0
while i < 100:
    i = i + 1
    if i == 5:
        continue
    if i == 10:
        break

Operators

Arithmetic Operators

var a = 10
var b = 3

var sum = a + b         # 13
var difference = a - b  # 7
var product = a * b     # 30
var quotient = a / b    # 3 (integer division)
var remainder = a % b   # 1

Comparison Operators

var x = 10
var y = 20

var equal = x == y        # false
var not_equal = x != y    # true
var less_than = x < y     # true
var less_equal = x <= y   # true
var greater_than = x > y  # false
var greater_equal = x >= y # false

Bitwise Operators

var a = 5   # 0101 in binary
var b = 3   # 0011 in binary

var and_result = a & b    # 1 (0001)
var or_result = a | b     # 7 (0111)
var xor_result = a ^ b    # 6 (0110)
var not_result = ~a       # bitwise NOT
var shift_left = a << 1   # 10
var shift_right = a >> 1  # 2

Built-in Functions

print

Output text to the console:

def greet() -> nil:
    print("Hello, World!")

ClientStore

The ClientStore is a built-in singleton that provides access to client inputs in MPC computations. It acts as the bridge between external clients and the secure computation.

ClientStore.get_number_clients()

Returns the total number of clients participating in the MPC computation.

# Returns a clear (non-secret) int64
var num_clients: int64 = ClientStore.get_number_clients()

Characteristics:

Returns a clear (public) int64 value, not a secret
Can be assigned to regular (non-secret) variables
Useful for dynamic iteration over client inputs

ClientStore.take_share()

Retrieves a secret share from a specific client at a given index.

# Parameters: (client_id, share_index)
secret var share1 = ClientStore.take_share(0, 0)  # Client 0, share 0
secret var share2 = ClientStore.take_share(1, 0)  # Client 1, share 0
secret var share3 = ClientStore.take_share(0, 1)  # Client 0, share 1

Parameters:

client_id: The ID of the client (0-indexed)
share_index: The index of the share from that client (0-indexed)

Critical Constraint: Results from ClientStore.take_share() must be assigned to secret variables. The compiler enforces this requirement for security. Valid usage patterns:

# 1. Using 'secret var' keyword (type inferred)
secret var share1 = ClientStore.take_share(0, 0)

# 2. Using explicit secret type annotation
var share2: secret int64 = ClientStore.take_share(1, 0)

# 3. Using 'secret' keyword with explicit type
secret var share3: int64 = ClientStore.take_share(0, 1)

# 4. Reassigning to existing secret variable
secret var mutable_share: int64 = ClientStore.take_share(0, 0)
mutable_share = ClientStore.take_share(1, 0)  # Valid: target is secret

Invalid usage (compiler errors):

# ERROR: Cannot assign take_share result to non-secret variable
var share: int64 = ClientStore.take_share(0, 0)

# ERROR: Implicit type doesn't make it secret
var share = ClientStore.take_share(0, 0)

# ERROR: Reassigning to non-secret variable
var regular_var: int64 = 42
regular_var = ClientStore.take_share(0, 1)

Error message: "ClientStore.take_share can only be assigned to secret variables" Hint: Add secret keyword to the variable declaration or use secret type annotation.

Working with Secret Types

Secret Arithmetic

def secure_calculation(a: secret int64, b: secret int64) -> secret int64:
    var result = a + b
    return result * 2

def mixed_operation(secret_val: secret int64, public_val: int64) -> secret int64:
    # Public values can be used with secrets
    return secret_val * public_val

MPC Input Pattern

Common pattern for processing client inputs:

def process_client_inputs() -> secret int64:
    # Get inputs from two clients
    secret var input1 = ClientStore.take_share(0, 0)
    secret var input2 = ClientStore.take_share(1, 0)

    # Perform secure computation
    return input1 + input2

main main() -> nil:
    var num_clients = ClientStore.get_number_clients()
    secret var result = process_client_inputs()
    print("Computation complete")

Complete Examples

Fibonacci (Iterative)

def fibonacci(n: int64) -> int64:
    if n <= 1:
        return n
    var a: int64 = 0
    var b: int64 = 1
    for i in 2..n:
        var temp = a + b
        a = b
        b = temp
    return b

main main() -> int64:
    return fibonacci(10)

Factorial (Recursive)

def factorial(n: int64) -> int64:
    if n <= 1:
        return 1
    return n * factorial(n - 1)

main main() -> int64:
    return factorial(5)  # Returns 120

Secure Sum

def secure_sum() -> secret int64:
    var num_clients = ClientStore.get_number_clients()
    secret var total: secret int64 = ClientStore.take_share(0, 0)

    # Note: In practice, you'd loop based on num_clients
    secret var input2 = ClientStore.take_share(1, 0)
    total = total + input2

    return total

main main() -> nil:
    secret var result = secure_sum()
    print("Sum computed")

Data Structures (Planned)

Object Types

Object types are parsed but have limited code generation support.

# Object type definition (planned)
type Person = object
    name: string
    age: int64

Enum Types

Enum types are parsed but have limited code generation support.

# Enum definition (planned)
type Status = enum
    Active
    Inactive
    Pending

Best Practices

Naming Conventions

# Use snake_case for variables and functions
var user_name = "alice"
var max_retry_count = 5

def calculate_total_cost(base_price: int64, tax_rate: int64) -> int64:
    return base_price + (base_price * tax_rate / 100)

# Use PascalCase for types (when supported)
type UserAccount = object
    user_id: int64

Secret Type Usage

# Clearly distinguish between public and secret data
def process_transaction(
    public_user_id: int64,
    secret_amount: secret int64
) -> secret int64:
    # Perform secure computation
    return secret_amount * 2

# Avoid using secrets in conditions (not allowed!)
# BAD: if secret_value > 0:  # This will fail!
# GOOD: Keep secret values in computations only

This syntax guide covers the current StoffelLang implementation. Features marked as “planned” are parsed by the compiler but may have limited code generation support.

Introduction

Getting Started

The Stoffel CLI

StoffelLang

StoffelVM

​Syntax and Examples

​Basic Elements

​Comments

​Identifiers and Keywords

​Variables and Types

​Variable Declarations

​Type Annotations

​Type Inference

​Primitive Types

​Integer Types

​Boolean Type

​String Type

​Nil Type

​Secret Types

​Functions

​Function Definitions

​Entry Point

​Function Calls

​Functions with Local Variables

​Control Flow

​If Statements

​While Loops

​For Loops

​Loop Control

​Operators

​Arithmetic Operators

​Comparison Operators

​Bitwise Operators

​Built-in Functions

​print

​ClientStore

​ClientStore.get_number_clients()

​ClientStore.take_share()

​Working with Secret Types

​Secret Arithmetic

​MPC Input Pattern

​Complete Examples

​Fibonacci (Iterative)

​Factorial (Recursive)

​Secure Sum

​Data Structures (Planned)

​Object Types

​Enum Types

​Best Practices

​Naming Conventions

​Secret Type Usage

Syntax and Examples

Basic Elements

Comments

Identifiers and Keywords

Variables and Types

Variable Declarations

Type Annotations

Type Inference

Primitive Types

Integer Types

Boolean Type

String Type

Nil Type

Secret Types

Functions

Function Definitions

Entry Point

Function Calls

Functions with Local Variables

Control Flow

If Statements

While Loops

For Loops

Loop Control

Operators

Arithmetic Operators

Comparison Operators

Bitwise Operators

Built-in Functions

print

ClientStore

ClientStore.get_number_clients()

ClientStore.take_share()

Working with Secret Types

Secret Arithmetic

MPC Input Pattern

Complete Examples

Fibonacci (Iterative)

Factorial (Recursive)

Secure Sum

Data Structures (Planned)

Object Types

Enum Types

Best Practices

Naming Conventions

Secret Type Usage