Crate overflow_proof

Monadic checked arithmetic for Rust

This library provides types wrapping raw numeric types, and tracking possibility of an overflow, enforcing correct handling without possibility of panics or incorrect values (when overflow checks in release build are disabled).

Checked is the main type provided by this library.

use overflow_proof::Checked;

let a = Checked::new(2u8);
let b = Checked::new(100u8);

// Aritmetic operations can be chained like with normal types
assert!({ ((a + 2) / 3 + 5) * b + 1}.check().is_none());
assert_eq!(*{ a + 2 + b }.check().expect("overflow"), 104);

use overflow_proof::{Checked, WithDeref};

struct OverflowError;

struct BankAccount {
  balance: Checked<u64, >,
}

impl BankAccount {
  fn debit(&mut self, amount: u64) -> Result<(), OverflowError> {
  // Will not compile:
  // Ok(self.balance -= amount)

  // Overflow must be checked:
  Ok(self.balance = {self.balance - amount}.check().ok_or(OverflowError)?)
  }
}

Structs

Checked

A wrapper around a numeric type, containing a valid value, that will perform overflow checks on arithmetic operations.

Unchecked

Intermediate result of artimetic operations on Checked value that might contain overflow

WithDeref

Marker for Checked that can be converted to the inner type semi-automatically.

WithoutDeref

Marker for Checked that must be explicitly converted to the inner type.

Traits

CheckedAbs

CheckedAdd

CheckedDiv

CheckedMul

CheckedNeg

CheckedRem

CheckedSub