Algorand TypeScript Rules

Critical syntax rules for Algorand TypeScript (PuyaTs) that prevent compiler errors and runtime failures.

File Extension: Contract files must use .algo.ts extension (e.g., Counter.algo.ts).

Overview / Core Workflow

1. Identify the syntax issue or pattern needed
2. Apply the correct AVM-compatible pattern
3. Use clone() for complex types
4. Verify no union types or JavaScript number

How to proceed

1. Check the most critical rules below
2. Consult detailed reference files for specific topics
3. Apply the correct pattern with proper AVM types
4. Build to verify: algokit project run build

Important Rules / Guidelines

Numbers: No JavaScript number

// CORRECT
const amount: uint64 = Uint64(20)
const total: uint64 = amount + Uint64(100)

// INCORRECT - Compiler error
const amount = 20

Numeric limits: Algorand TypeScript supports integers up to 2^512. Use biguint for values exceeding uint64 (2^64 - 1).

Value Semantics: Always clone()

import { clone } from '@algorandfoundation/algorand-typescript'

const state = clone(this.appState.value)     // Read: clone
const updated = clone(state)                  // Modify: clone
this.appState.value = clone(updated)          // Write: clone

No Union Types

// CORRECT - Use boolean flags
let found = false
let foundItem: Item = { /* defaults */ }

// INCORRECT - Compiler error
let foundItem: Item | null = null

Arrays: Clone Before Iterating

// CORRECT
for (const item of clone(array)) { }

Common Variations / Edge Cases

References / Further Reading

Detailed rules by topic:

• Types and Values — AVM types, numbers, clone(), value semantics
• Storage — GlobalState, LocalState, BoxMap, MBR funding
• Methods and ABI — Decorators, lifecycle methods, visibility
• Transactions — Group transactions (gtxn), inner transactions (itxn)
• Full Reference Index