Josef Pospíšil
CTO at LastStar.eu. s.r.o.
Liberec, Northeast, Czechia
Summary
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Rockstar🎓
Top SchoolJosef Pospíšil is a seasoned technology leader and entrepreneur with 16 years of hands-on experience building web and mobile systems, currently serving as CTO and owner at LastStar.eu. He has longstanding expertise in Ruby and Ruby on Rails as well as iOS development, and previously led engineering and product efforts as CTO at GravaStar and a senior developer exploring web-enabled MES at Merz. Josef combines academic and practical perspectives—he served as Head of IT and Simulation Technology at the Technical University of Liberec—and holds a Master’s in Informatics. An active open-source contributor, he has improved core functionality and tests in the Janet language VM, showing attention to low-level library correctness beyond typical web work. He’s comfortable moving between strategic leadership, hands-on backend fixes, and documentation/test improvements, making him effective at stabilizing and scaling engineering teams. Based in Liberec, Czechia, he brings entrepreneurial grit evidenced by founding and financing multiple ventures while maintaining a developer-first approach.
16 years of coding experience
7 years of employment as a software developer
Master, Informatics, Master, Informatics at Czech University of Life Sciences PragueAutomatization, Automatization at Střední průmyslová škola strojní a elektrotechnická v Liberci
English, Polish, Russian, Slovak
Stackoverflow
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Github Skills (12)
c1710
c1110
lisp9
functional9
functional-programming-language9
interpreter9
macros9
lang9
functional-programming9
testing8
vms8
assembly6
Programming languages (18)
Github contributions (5)
janet-lang/janet
Feb 2020 - Aug 2022
A dynamic language and bytecode vm
Role in this project:
Back-end Developer
Back-end DeveloperContributions:92 reviews, 25 commits, 33 PRs in 2 years 7 months
Contributions summary:Josef primarily contributed to bug fixes and feature enhancements for the Janet programming language. Their work included correcting function arities, fixing typos, adding tests, and improving documentation. Several commits focused on core library functionalities like `last` and `reverse`, indicating involvement in the language's fundamental components. The user also implemented tests for PEG-related functions and added functionality to the numarray example.
functional-languagexmakemacrosc-programmingscripting-language
pepe/spork
Apr 2020 - Dec 2024
Various Janet utilliy modules.
Contributions:52 pushes, 44 branches in 4 years 8 months
janet
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