This talk describes about code positions on Ruby.
Code positions are new location information of AST Nodes, introduced from Ruby 2.5.
Code positions enable us to improve warning messages, exception messages, `Proc#source_location` and so on.
This talk includes the following topics.
* What code positions are.
* Why they are needed.
* How they are implemented.
RubyKaigi 2018 https://rubykaigi.org/2018/presentations/spikeolaf
RubyKaigi 2018