Meeting - 9th April 2018

[jacqueswww]

Meeting Details

General Bi-Weekly meeting.
Start: Monday 9th April 2018, 14:00 UTC (https://time.is/UTC)
Hangouts: https://meet.google.com/czc-kuep-jda

Agenda

• Assignment to tuple not supported #727 - Tuple assign, post or pre beta?
• Add 'python_requires' to setup.py #665
• Need support for integer division in Vyper #716 - Integer Division
• Disallow implicit conversion during comparison #737 - Disallow implicit conversion
• VIP Discussions:
  • VIP: Enable Dynamic Analysis/Symbolic Execution Checks #711 - Assertions that should never-ever fail
  • VIP: Allow list of byte arrays #728 - Allow list of byte arrays
  • VIP: remove reduntand syntax for address to contract #748 - Remove reduntand syntax for address to contract
  • VIP: remove casting in signature #749 - Remove casting in signature
  • VIP: Require compiler flag for nonstandard primitive types #750 - Require compiler flag for nonstandard primitive types
  • None in viper is misleading #539 - None in viper is misleading
  • VIP: Allow declaring custom units #752 - Allow declaring custom units
  • VIP: Change binary literal format #732 - Change binary literal format
  • VIP: uint256 as a first class citizen #764 - uin256 as first class citizen
• shift discussion

[jacqueswww]

Feel free to comment any additional agenda items here.

[ben-kaufman]

Not sure I will be able to join the call.
Anyway I think we should add #752 to the VIP Discussions.

[yzhang90]

Improving shift function.

shift is compiled to the following code:

   ['if', ['sle', '_s', 0], 
          ['div', '_v', ['exp', 2, ['sub', 0, '_s']]], 
          ['mul', '_v', ['exp', 2, '_s']]]]],

When _s == 0, ['div', '_v', ['exp', 2, ['sub', 0, '_s']]] and ['mul', '_v', ['exp', 2, '_s']]]] are the same. But in the div branch, it need to execute sub which potentially costs more gas. Suggest using slt instead of sle. This will also ease the verification. On the other hand, EIP145 proposes supporting shift opcode directly in EVM. Not sure when it will happen.

[jacqueswww]

@yzhang90 Please create the two tickets/bugs you have discovered, much appreciated 😄

[jacqueswww]

https://github.com/kframework/vyper-semantics/wiki/Vyper-language-features