VIP: Add min and max type

[fubuloubu]

Simple Summary

Add the ability to get the minimum and maximum values for a given type via min_value(type) and max_value(type). Remove value constants like ZERO_ADDRESS, MIN_UINT256, and EMPTY_BYTES32

Motivation

#1675 adds empty(type) to specify an empty section of memory filling the size of type. This can be used to simulate "default" values that the EVM provides all types. Some types deserve the ability to also specify their edge-case values, so functionality should be added to ensure this is possible. After this featureset is fully implemented, it makes sense to eliminate the standard constants that are provided with Vyper, as they can be replicated with this more advanced featureset

Specification

min_value(type)

Returns the minimum representation value of the given type (the most negative value for a given type). Raises a compilation error if the type does not have a minimum representation type (like bytes32 or address)

Throws for more complex types.

max_value(type)

Returns the maximum representation value of the given type (the most positive value for a given type). Raises a compilation error if the type does not have a maximum representation type (like bytes32 or address)

Throws for more complex types.

Built-in Constants

All built-in constants can be replicated as follows:

ZERO_ADDRESS: address = empty(address)
EMPTY_BYTES32: bytes32 = empty(bytes32)
MAX_INT128: int128 = max_value(int128)
MIN_INT128: int128 = min_value(int128)
MAX_DECIMAL: decimal = max_value(decimal)
MIN_DECIMAL: decimal = min_value(decimal)
MAX_UINT256: uint256 = max_value(uint256)
MIN_UINT256: uint256 = min_value(uint256)  # Same as empty(uint256)

Backwards Compatibility

Removes built-in constants

Dependencies

No dependencies

Copyright

Copyright and related rights waived via CC0

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EDIT: Modified min and max to min_value and max_value

[charles-cooper]

great VIP!

[iamdefinitelyahuman]

I like the functionality but I'm not a fan of the names. Vyper already uses min and max as arithmetic functions returning the lower or higher of two numeric values. As described, this VIP will give these functions two completely different functionalities depending on the input(s) given.

Is there another set of function names that are just as descriptive and not already in use?

[fubuloubu]

We can just do min_value(type) and max_value(type), which are much more descriptive

[iamdefinitelyahuman]

👍 for min_value and max_value