Rikito Taniguchi



  • 5 years of experience in web development with Computer Science knowledge.
  • Enthusiastic OSS developer, primarily in Scala developer tools (formatter/IDE/linter).
  • Good at untangling big software and writing maintainable code and documents.
  • Cross-functional communicator with empathy.


  • Languages I often use
    • Scala, TypeScript
  • Languages I experienced with
    • Go, Python, Perl, OCaml


  • Master in Computer Science, Tokyo Institute of Technology (2021/04 - Present)
  • Bachelor in Computer Science, Kyoto University (2013/04 - 2017/03)

Employment History

Google Summer of Code (2021/06 - 2021/08)

Add synthetics and symbol information for semanticdb in Scala 3

  • Developed the feature that exports semantic information (SemanticDB) from Scala3 compiler for devtools (such as linter and IDE).
    • This work improved developer experience for Scala3 by unlocking IDE features such as find-references, show inferred types, and go-to-implementation.
  • Full report is available here.

Hatena (2017/04 - 2021/08)

Replace legacy monolithic Perl application to Scala

  • Presentation slide at ScalaMatsuri 2019
  • Revitalized the unmaintainable SNS software by
    • replacing core logic using Scala
    • re-design the DB schema
    • deconstruct the monolithic Perl application to SOA.
  • My main contributions
    • Untangled big unmaintained software and list up functional requirements and non-function requirements.
    • Developed server application using Scala, Go, and Perl.
    • Developed frontend using TypeScript.
    • Designed MySQL database schema and did database migration using Embulk.

Develop and maintain inappropriate contents detection system.

  • Developed a system that helps user-support team to find and deal with inappropriate uploaded content to our SNS (e.g., blog posts, image file).
  • My main contributions
    • Developed server application using TypeScript, Terraform+GCP (GAE, IAP, PubSub, Tasks, Functions, Datastore), json schema.
    • Build admin page’s frontend using TypeScript, React, and GraphQL.
    • Construct a simple data pipeline on GCP and analyze data using BigQuery to maximize the cost-effectiveness of the system.

Notable Open Source contributions

  • lampepfl/dotty
    • Developed the feature that pickles semantic information (SemanticDB) to improve the Scala3 developer experience.
  • scalameta/metals
    • Developed various IDE features such as Scaladoc completion, implement abstract members, and Scala3’s completion improvement.
  • scalameta/scalafmt
    • Made scalafmt’s version configurable, to align the formatter behavior across the plugins (IDE, sbt plugin, and CLI).
    • Various bug fixes