Futhark by Example

The following is a hands-on introduction to Futhark through a collection of commented programs, listed in roughly increasing order of complexity. You can load the programs into the interpreter to experiment with them. For a conventional introduction to the language, Parallel Programming in Futhark may be a better choice. For more examples, you can check our implemented benchmarks. We also maintain a list of projects using Futhark.Some of the example programs use directives for plotting or rendering graphics.Basic language features Basic usage with the factorial function Primitive values Converting a value to a different type Mathematical functions Functions Arrays Minimum and maximum Type ascriptions Basic parallelism Tuples and records Size coercions Ranges Backtick operators Scans and reductions Parametric polymorphism Polymorphic minimum and maximum Gather and scatter Exclusive scans Exclusive prefix sum Pipe operators Complex ranges Sum types and pattern matching Loops Flattening and unflattening arrays In-place updates Programming techniques Benchmarking Counting elements that satisfy property Index of smallest element (argmin) Reducing the result of a filter Scattering the result of a filter Size parameters Matrix multiplication Pairwise L₁ distances Outer product Comparing arrays for equality Searching Option type Computing histograms Moving average Means Swapping two elements of an array Integer logarithm Radix sort Radix sort by key Merge sort Removing duplicates Abstract data types Complex numbers Testing for associativity Reducing or scanning without a neutral element Holes Kahan summation Random numbers Gaussian blur (with Python integration) Three-dimensional vectors Faking nominal types Triangular matrices Binary search AD with dual numbers Variance Matching parentheses Evaluating polynomials Line fitting Decoding MNIST data files Automatic differentiation Forward-mode automatic differentiation Reverse-mode automatic differentiation Newton’s Method Literate Futhark Basic use of literate Futhark Generating videos with literate Futhark Reading and writing files in literate Futhark PlottingLiterate Futhark allows direct use of gnuplot.

These examples show simple and common cases. Plotting a histogram Examples from DexThe following examples are ported from Dex, a dependently typed functional array language that uses a somewhat different approach to describing loop processing. We've tried to keep the original naming scheme and programming style. Prelude Mandelbrot set Multi-step ray tracer Monte Carlo estimates of pi Brownian motion Sierpinski triangle External examples OCaml-GPU wordcount example by calling Futhark. Projects using FutharkThe majority of written Futhark code is probably still Futhark’s own test and benchmark suites. However, there are some programs that have been written in Futhark because it was a good tool for the job, and not just to test the compiler. A possibly incomplete list:Diving Beet is a falling sand game, which is a kind of simple particle simulator toy. Its main purpose is to produce pretty effects. There is a blog post with details and a video.Futball is a game about avoiding getting hit by balls. The rendering engine is a ray tracer written in Futhark.Futcam is an application that applies stacks of interactively configurable filters to a webcam stream. Futhark is used to implement the filters.Futracer is a fairly slow brute-force ray tracer written in Futhark.Futswirl is a fractal generator based on iterated function systems.Neptune is an implementation of the Poseidon hash function tuned for Filecoin, where the GPU parts have been implemented in Futhark.Palathark is a Futhark implementation of the lattice Boltzmann method.Ray Tracing in One Weekend in Futhark and Ray Tracing: the Next Week in Futhark are implementations based on Peter Shirley's book series. These are by no means real-time ray tracers, but support advanced effects and make use of acceleration structures like BVH trees.Pareas is a compiler implemented in Futhark and C++.