26. Type conversions with convert()

Vyper never converts types implicitly. `convert(value, TargetType)` performs a checked conversion, reverting if the value can't be represented in the target type (e.g. converting a negative `int256` to `uint256`).

@external
@pure
def to_uint(x: int128) -> uint256:
    assert x >= 0, "negative value"
    return convert(x, uint256)

@external
@pure
def to_bytes(x: uint256) -> bytes32:
    return convert(x, bytes32)

Because conversions are checked, they double as a lightweight assertion — a failed `convert()` is a clear signal something upstream produced an unexpected value.

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