Interpreters

The original Homespring specification shipped with an interpreter and another implementation was created the next day. This page documents all of the known interpreter implementations, along with a compatibility matrix showing which interpreters can run which of the collected example programs.

Programs are grouped by author and listed under their original filenames.

The Interpreters

41%

Guile Scheme 2003-04-14

Jeff Binder

github.com/iamcal/Homespring

The original reference implementation.

17%

Perl 2003-04-15

Cal Henderson

github.com/iamcal/perl-Language-Homespring

The first third party interpreter, including a tree visualizer.

100%

OCaml 2005-11-24

Joe Neeman

github.com/jneem/homespring

Released along with an updated spec.

59%

JavaScript 2012-10-30

Quin Kennedy

github.com/quinkennedy/Homespring

The first JavaScript implementation.

100%

JavaScript 2017-01-29

Cal Henderson

github.com/iamcal/homespring.js

The implementation that powers this website.

Rust 2017-12-19

Addison Bean

github.com/Addisonbean/Homespring-rs

An incomplete WIP — parses programs, but only a few node types and ticks are implemented.

JavaScript 2018-05-30

Martijn Arts

github.com/martijnarts/homespring-js

A demo implementation with HTML visualizer.

28%

JavaScript 2023-01-02

James Thistlewood

github.com/jthistle/homespring-visualizer

A browser visualizer with an embedded interpreter; driven headlessly here.

The Example Programs

Example	Description	Scheme200341%	Perl200317%	OCaml2005100%	JavaScript201259%	JavaScript2017100%	Rust20173%	JavaScript20183%	JavaScript202328%
Jeff Binder — 2003 · author of Homespring and its original Scheme interpreter
add.hs	Reads two numbers from input and outputs their sum.	yes	no	yes	yes^*	yes	no	no	no
cat.hs	Echoes its input straight to output, like the Unix `cat` utility.	yes	no	yes	yes^*	yes	no	no	no
first.hs	A minimal "Hello, world" — a single hatchery feeding a bear.	yes	yes	yes	yes^*	yes	no	no	yes
hello-1.hs	"Hello, World!" using a universe, a hatchery, and snowmelt-powered rapids.	yes	yes	yes	yes^*	yes	no	no	yes
hello-2.hs	"Hello, World!" — an alternative arrangement using the power-override rule.	yes	yes	yes	yes^*	yes	no	no	yes
hello-3.hs	"Hello, World!" using marshy force, field-sense shallows, and a hydro-power spring.	yes	no	yes	yes^*	yes	no	no	no
hi.hs	Prompts the user for their name and greets them back with a "Hi".	yes	no	yes	yes^*	yes	no	no	no
name.hs	An acrostic program whose node names spell out HOMESPRING line by line.	no	no	yes	no	yes	no	no	no
null.hs	The empty program — zero bytes, does nothing.	yes	no	yes	yes^*	yes	no	no	no
quiz.hs	A tiny maths quiz that asks "what's six times four?" and grades the reply.	yes	no	yes	yes^*	yes	no	no	no
simple.hs	The simplest possible non-empty program — a single node.	yes	yes	yes	yes	yes	yes	yes	yes
Cal Henderson — 2003 · author of the Perl interpreter
hello2.hs	A compact "Hello, World!" — shipped with the Perl interpreter as a test program.	yes	yes	yes	yes^*	yes	no	no	yes
Joe Neeman — 2005 · author of the OCaml interpreter
flipflop.hs	A flip-flop that alternates state using an inverse-lock and a pair of pump/switch nodes.	no	no	yes	no	yes	no	no	no
tic.hs	A tic-tac-toe implementation — the most elaborate program in the collection.	no	no	yes	no	yes	no	no	no
Quin Kennedy — 2012 · author of a JavaScript interpreter
reverse.hsg	Reverses the input using a `force.up` node and a `split`.	Quin's example files don't run correctly on compliant interpreters, due to two important mistakes in the implementation. The `reverse*.hsg` examples rely on the `force up` node allowing upstream salmon to move to the first child, which it should be blocking. The `split.hsg` example relies on an incorrect implementation of `append up` where the appending logic is supposed to run in the misc tick, but instead runs in the fish tick down, before any upstream salmon have had a chance to arrive (or leave, from the previous tick).
reverse-2.hsg	Reverses the input — a more poetic variant ("split wings calm the ebb and flow").
reverse-3.hsg	Reverses the input — a third variation of the same arrangement.
split.hsg	Splits input into pieces.
Benito van der Zander — 2013 · author of the HomeSpringTree compiler; most are generated from HomeSpringTree (.hst) sources
clock.hs(.hst)	A ticking clock driven by the `time` node and a range-switch cascade.	no	no	yes	yes^*	yes	no	no	no
count.hs(.hst)	Counts from 0 to 9 and then to 100 using a bridged bear and hatchery cascade.	no	no	yes	yes^*	yes	no	no	no
count2.hs(.hst)	A more elaborate counter built from digit generators.	no	no	yes	no	yes	no	no	no
count3.hs(.hst)	Another counter variant.	no	no	yes	no	yes	no	no	no
count4.hs(.hst)	A larger counter implementation (~10 KB of source).	no	no	yes	no	yes	no	no	no
count.poem.hs(.hst)	A counter written in the poetic style Homespring is intended to be read in.	no	no	yes	yes^*	yes	no	no	no
count.poem.withfillers.hs	A poetic counter with additional filler words for extra flow.	no	no	yes	yes^*	yes	no	no	no
fizzbuzz.hs(.hst)	Classic FizzBuzz — prints Fizz for multiples of 3, Buzz for 5, FizzBuzz for both.	no	no	yes	no	yes	no	no	no
fizzbuzz.poem.hs(.hst)	FizzBuzz written in the poetic style — considerably longer.	no	no	yes	no	yes	no	no	no
fizzbuzztick.hs(.hst)	A compact FizzBuzz variant driven by time ticks.	no	no	yes	no	yes	no	no	no
helloworld.hs(.hst)	A fourth take on "Hello, World!" — generated from a HomeSpringTree source.	no	no	yes	yes^*	yes	no	no	yes
Cal Henderson — 2026 · focused tests for this harness, each written to exercise one node whose behaviour the older programs barely touched
test-waterfall.hs	Upstream salmon are blocked by the `waterfall` and spawn there instead of climbing to the leaf.	no	no	yes	no	yes	no	no	no
test-clone.hs	`clone` duplicates each passing salmon, so every cycle emits multiple `homeless` before `Hello`.	no	no	yes	no	yes	no	no	yes
test-young-bear.hs	`young. bear` eats every other mature salmon, letting only half the `homeless` fish reach the root.	no	no	yes	no	yes	no	no	no
test-spawn.hs	`spawn` forces upstream salmon to spawn in place, so the output is the node's own name.	yes	no	yes	yes^*	yes	no	no	yes

yes runs correctly yes runs correctly, with caveats (hover for details) no does not run correctly (hover for details) ? no canonical expected output

^* Quin Kennedy's interpreter appends an extra newline to every output — the program produces the correct text but with one trailing \n beyond what the other interpreters emit.

Compatibility data is generated by the test harness in tests/, which runs every example above under every interpreter and writes per-adapter reports under tests/results/. Hover over a cell for further details about that specific result. The full interpreter source repositories are checked in as submodules under interpreters/.