We chat with Stefan Karpinski, creator of the Julia programming language, live on stage during Øredev 2014. Topics include deciding to build a new language, the interesting unsolved problems of numerical computing, concurrency solutions, developing with and on LLVM, handling deprecation nicely, things (possibly) in the future for Julia and why Swift is exciting for Julia and other languages.

This recording exists as good as it is thanks to Stephen Chin of nighthacking.com for providing and masterfully wrangling all the necessary technology.

There is a minute and a half of worse audio quality just after the nine minute mark, where microphone problems forced us to fill in with audio from our backup microphone.

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Links

Stefan Karpinski Julia programming language Scientific computing Viral Shah Jeff Bezanson MATLAB R • programming language

Python C extension Goldilocks Goldilocks principle Dylan Garbage collection Unboxed data Complex number Julia Webstack Numerical computing Concurrency Distributed computing Threading Julia on Github Transactional memory Goroutine Coroutine Channel I/O LLVM IFDEF JIT • - just-in-time (compilation, in this case)

Shared library libclang • - C Interface to Clang

Template instantiation Quake2.jl Go Hacker school Matrix multiplication Vectorization Generational incremental garbage collection SNOBOL SPITBOL Icon Perl 4 C99 standard Immutable composite types Multiple dispatch Monkey patch radd • -trick in Python

Common Lisp CLOS • - Common Lisp object system

Polymorphism Self BLAS • - Basic linear algebra subroutines

Fast fourier transform Gofix Tracing Static compilation MIT • - Massachusetts institute of technology

Courses taught using Julia Function pointer Scipy Steven Johnson FFTW Pycall package for Julia Call stack GDB LLDB ABI • - application binary interface

Clang Rust programming language Swift Chris Lattner • - creator of LLVM and Swift

WebKit FTL JIT • - compiles Javascript using LLVM

Shadow stack ‎Dynamic stack frame deoptimization MATLAB matrix concatenation syntax

Titles

• Some of the interesting tradeoffs

• Bridge that gap between high-level and low-level

• A huge pointer graph of some kind

• It’s good to have a focus, initially

• The point where we’re pushing things

• The classic tradition of a ton of IFDEFs

• This brings us back to garbage collection

• Specializing for numerical work

• Where numbers don’t have to be special anymore

• (The question is:) How useful is that generalization?

• You don’t necessarily know what code you’re going to need in advance

• Trading off memory for performance

• Really doing the deprecation process

• A situation where normally you’d JIT something

• You might end up in a slow case

• You can always just fall back on an interpreter

• A partially compiled interpreter

• Nobody needs to know that it was written in Julia

• A really capable C library

• As easy as walking a linked pointer list

• I’m really glad someone else implemented it