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-rw-r--r--chapter-7/.dir-locals.el3
-rw-r--r--chapter-7/Makefile8
-rw-r--r--chapter-7/hoot/reflect.js738
-rw-r--r--chapter-7/hoot/reflect.wasmbin0 -> 5196 bytes
-rw-r--r--chapter-7/hoot/wtf8.wasmbin0 -> 1071 bytes
-rw-r--r--chapter-7/index.html26
-rw-r--r--chapter-7/manifest.scm24
-rw-r--r--chapter-7/propagators.css38
-rw-r--r--chapter-7/propagators.js30
-rw-r--r--chapter-7/propagators.scm659
10 files changed, 1526 insertions, 0 deletions
diff --git a/chapter-7/.dir-locals.el b/chapter-7/.dir-locals.el
new file mode 100644
index 0000000..95249a0
--- /dev/null
+++ b/chapter-7/.dir-locals.el
@@ -0,0 +1,3 @@
+((scheme-mode
+ .
+ ((eval . (put 'with-cells 'scheme-indent-function 1)))))
diff --git a/chapter-7/Makefile b/chapter-7/Makefile
new file mode 100644
index 0000000..15a88da
--- /dev/null
+++ b/chapter-7/Makefile
@@ -0,0 +1,8 @@
+propagators.wasm: propagators.scm
+ guild compile-wasm -o $@ $<
+
+serve: propagators.wasm
+ guile -c '((@ (hoot web-server) serve))'
+
+clean:
+ rm -f propagators.wasm
diff --git a/chapter-7/hoot/reflect.js b/chapter-7/hoot/reflect.js
new file mode 100644
index 0000000..b00874c
--- /dev/null
+++ b/chapter-7/hoot/reflect.js
@@ -0,0 +1,738 @@
+// -*- js2-basic-offset: 4 -*-
+class Char {
+ constructor(codepoint) {
+ this.codepoint = codepoint;
+ }
+ toString() {
+ let ch = String.fromCodePoint(this.codepoint);
+ if (ch.match(/[a-zA-Z0-9$[\]().]/)) return `#\\${ch}`;
+ return `#\\x${this.codepoint.toString(16)}`;
+ }
+}
+class Eof { toString() { return "#<eof>"; } }
+class Nil { toString() { return "#nil"; } }
+class Null { toString() { return "()"; } }
+class Unspecified { toString() { return "#<unspecified>"; } }
+
+class Complex {
+ constructor(real, imag) {
+ this.real = real;
+ this.imag = imag;
+ }
+ toString() {
+ const sign = this.imag >= 0 && Number.isFinite(this.imag) ? "+": "";
+ return `${flonum_to_string(this.real)}${sign}${flonum_to_string(this.imag)}i`;
+ }
+}
+class Fraction {
+ constructor(num, denom) {
+ this.num = num;
+ this.denom = denom;
+ }
+ toString() {
+ return `${this.num}/${this.denom}`;
+ }
+}
+
+class HeapObject {
+ constructor(reflector, obj) {
+ this.reflector = reflector;
+ this.obj = obj;
+ }
+ repr() { return this.toString(); } // Default implementation.
+}
+
+class Pair extends HeapObject {
+ toString() { return "#<pair>"; }
+ repr() {
+ let car_repr = repr(this.reflector.car(this));
+ let cdr_repr = repr(this.reflector.cdr(this));
+ if (cdr_repr == '()')
+ return `(${car_repr})`;
+ if (cdr_repr.charAt(0) == '(')
+ return `(${car_repr} ${cdr_repr.substring(1)}`;
+ return `(${car_repr} . ${cdr_repr})`;
+ }
+}
+class MutablePair extends Pair { toString() { return "#<mutable-pair>"; } }
+
+class Vector extends HeapObject {
+ toString() { return "#<vector>"; }
+ repr() {
+ let len = this.reflector.vector_length(this);
+ let out = '#(';
+ for (let i = 0; i < len; i++) {
+ if (i) out += ' ';
+ out += repr(this.reflector.vector_ref(this, i));
+ }
+ out += ')';
+ return out;
+ }
+}
+class MutableVector extends Vector {
+ toString() { return "#<mutable-vector>"; }
+}
+
+class Bytevector extends HeapObject {
+ toString() { return "#<bytevector>"; }
+ repr() {
+ let len = this.reflector.bytevector_length(this);
+ let out = '#vu8(';
+ for (let i = 0; i < len; i++) {
+ if (i) out += ' ';
+ out += this.reflector.bytevector_ref(this, i);
+ }
+ out += ')';
+ return out;
+ }
+}
+class MutableBytevector extends Bytevector {
+ toString() { return "#<mutable-bytevector>"; }
+}
+
+class Bitvector extends HeapObject {
+ toString() { return "#<bitvector>"; }
+ repr() {
+ let len = this.reflector.bitvector_length(this);
+ let out = '#*';
+ for (let i = 0; i < len; i++) {
+ out += this.reflector.bitvector_ref(this, i) ? '1' : '0';
+ }
+ return out;
+ }
+}
+class MutableBitvector extends Bitvector {
+ toString() { return "#<mutable-bitvector>"; }
+}
+
+class MutableString extends HeapObject {
+ toString() { return "#<mutable-string>"; }
+ repr() { return string_repr(this.reflector.string_value(this)); }
+}
+
+class Procedure extends HeapObject {
+ toString() { return "#<procedure>"; }
+ call(...arg) {
+ return this.reflector.call(this, ...arg);
+ }
+ async call_async(...arg) {
+ return await this.reflector.call_async(this, ...arg);
+ }
+}
+
+class Sym extends HeapObject {
+ toString() { return "#<symbol>"; }
+ repr() { return this.reflector.symbol_name(this); }
+}
+
+class Keyword extends HeapObject {
+ toString() { return "#<keyword>"; }
+ repr() { return `#:${this.reflector.keyword_name(this)}`; }
+}
+
+class Variable extends HeapObject { toString() { return "#<variable>"; } }
+class AtomicBox extends HeapObject { toString() { return "#<atomic-box>"; } }
+class HashTable extends HeapObject { toString() { return "#<hash-table>"; } }
+class WeakTable extends HeapObject { toString() { return "#<weak-table>"; } }
+class Fluid extends HeapObject { toString() { return "#<fluid>"; } }
+class DynamicState extends HeapObject { toString() { return "#<dynamic-state>"; } }
+class Syntax extends HeapObject { toString() { return "#<syntax>"; } }
+class Port extends HeapObject { toString() { return "#<port>"; } }
+class Struct extends HeapObject { toString() { return "#<struct>"; } }
+
+function instantiate_streaming(path, imports) {
+ if (typeof fetch !== 'undefined')
+ return WebAssembly.instantiateStreaming(fetch(path), imports);
+ let bytes;
+ if (typeof read !== 'undefined') {
+ bytes = read(path, 'binary');
+ } else if (typeof readFile !== 'undefined') {
+ bytes = readFile(path);
+ } else {
+ let fs = require('fs');
+ bytes = fs.readFileSync(path);
+ }
+ return WebAssembly.instantiate(bytes, imports);
+}
+
+class Scheme {
+ #instance;
+ #abi;
+ constructor(instance, abi) {
+ this.#instance = instance;
+ this.#abi = abi;
+ }
+
+ static async reflect(abi, {reflect_wasm_dir = '.'}) {
+ let debug = {
+ debug_str(x) { console.log(`reflect debug: ${x}`); },
+ debug_str_i32(x, y) { console.log(`reflect debug: ${x}: ${y}`); },
+ debug_str_scm: (x, y) => {
+ console.log(`reflect debug: ${x}: #<scm>`);
+ },
+ };
+ let reflect_wasm = reflect_wasm_dir + '/reflect.wasm';
+ let rt = {
+ die(tag, data) { throw new SchemeTrapError(tag, data); },
+ wtf8_to_string(wtf8) { return wtf8_to_string(wtf8); },
+ string_to_wtf8(str) { return string_to_wtf8(str); },
+ };
+ let { module, instance } =
+ await instantiate_streaming(reflect_wasm, { abi, debug, rt });
+ return new Scheme(instance, abi);
+ }
+
+ #init_module(mod) {
+ mod.set_debug_handler({
+ debug_str(x) { console.log(`debug: ${x}`); },
+ debug_str_i32(x, y) { console.log(`debug: ${x}: ${y}`); },
+ debug_str_scm: (x, y) => {
+ console.log(`debug: ${x}: ${repr(this.#to_js(y))}`);
+ },
+ });
+ mod.set_ffi_handler({
+ procedure_to_extern: (obj) => {
+ const proc = this.#to_js(obj);
+ return (...args) => {
+ return proc.call(...args);
+ };
+ }
+ });
+ let proc = new Procedure(this, mod.get_export('$load').value);
+ return proc.call();
+ }
+ static async load_main(path, opts = {}) {
+ let mod = await SchemeModule.fetch_and_instantiate(path, opts);
+ let reflect = await mod.reflect(opts);
+ return reflect.#init_module(mod);
+ }
+ async load_extension(path, opts = {}) {
+ opts = Object.assign({ abi: this.#abi }, opts);
+ let mod = await SchemeModule.fetch_and_instantiate(path, opts);
+ return this.#init_module(mod);
+ }
+
+ #to_scm(js) {
+ let api = this.#instance.exports;
+ if (typeof(js) == 'number') {
+ return api.scm_from_f64(js);
+ } else if (typeof(js) == 'bigint') {
+ if (BigInt(api.scm_most_negative_fixnum()) <= js
+ && js <= BigInt(api.scm_most_positive_fixnum()))
+ return api.scm_from_fixnum(Number(js));
+ return api.scm_from_bignum(js);
+ } else if (typeof(js) == 'boolean') {
+ return js ? api.scm_true() : api.scm_false();
+ } else if (typeof(js) == 'string') {
+ return api.scm_from_string(js);
+ } else if (typeof(js) == 'object') {
+ if (js instanceof Eof) return api.scm_eof();
+ if (js instanceof Nil) return api.scm_nil();
+ if (js instanceof Null) return api.scm_null();
+ if (js instanceof Unspecified) return api.scm_unspecified();
+ if (js instanceof Char) return api.scm_from_char(js.codepoint);
+ if (js instanceof HeapObject) return js.obj;
+ if (js instanceof Fraction)
+ return api.scm_from_fraction(this.#to_scm(js.num),
+ this.#to_scm(js.denom));
+ if (js instanceof Complex)
+ return api.scm_from_complex(js.real, js.imag);
+ return api.scm_from_extern(js);
+ } else if (typeof(js) == 'function') {
+ return api.scm_from_extern(js);
+ } else {
+ throw new Error(`unexpected; ${typeof(js)}`);
+ }
+ }
+
+ #to_js(scm) {
+ let api = this.#instance.exports;
+ let descr = api.describe(scm);
+ let handlers = {
+ fixnum: () => BigInt(api.fixnum_value(scm)),
+ char: () => new Char(api.char_value(scm)),
+ true: () => true,
+ false: () => false,
+ eof: () => new Eof,
+ nil: () => new Nil,
+ null: () => new Null,
+ unspecified: () => new Unspecified,
+ flonum: () => api.flonum_value(scm),
+ bignum: () => api.bignum_value(scm),
+ complex: () => new Complex(api.complex_real(scm),
+ api.complex_imag(scm)),
+ fraction: () => new Fraction(this.#to_js(api.fraction_num(scm)),
+ this.#to_js(api.fraction_denom(scm))),
+ pair: () => new Pair(this, scm),
+ 'mutable-pair': () => new MutablePair(this, scm),
+ vector: () => new Vector(this, scm),
+ 'mutable-vector': () => new MutableVector(this, scm),
+ bytevector: () => new Bytevector(this, scm),
+ 'mutable-bytevector': () => new MutableBytevector(this, scm),
+ bitvector: () => new Bitvector(this, scm),
+ 'mutable-bitvector': () => new MutableBitvector(this, scm),
+ string: () => api.string_value(scm),
+ 'mutable-string': () => new MutableString(this, scm),
+ procedure: () => new Procedure(this, scm),
+ symbol: () => new Sym(this, scm),
+ keyword: () => new Keyword(this, scm),
+ variable: () => new Variable(this, scm),
+ 'atomic-box': () => new AtomicBox(this, scm),
+ 'hash-table': () => new HashTable(this, scm),
+ 'weak-table': () => new WeakTable(this, scm),
+ fluid: () => new Fluid(this, scm),
+ 'dynamic-state': () => new DynamicState(this, scm),
+ syntax: () => new Syntax(this, scm),
+ port: () => new Port(this, scm),
+ struct: () => new Struct(this, scm),
+ 'extern-ref': () => api.extern_value(scm)
+ };
+ let handler = handlers[descr];
+ return handler ? handler() : scm;
+ }
+
+ call(func, ...args) {
+ let api = this.#instance.exports;
+ let argv = api.make_vector(args.length + 1, api.scm_false());
+ func = this.#to_scm(func);
+ api.vector_set(argv, 0, func);
+ for (let [idx, arg] of args.entries())
+ api.vector_set(argv, idx + 1, this.#to_scm(arg));
+ argv = api.call(func, argv);
+ let results = [];
+ for (let idx = 0; idx < api.vector_length(argv); idx++)
+ results.push(this.#to_js(api.vector_ref(argv, idx)))
+ return results;
+ }
+
+ call_async(func, ...args) {
+ return new Promise((resolve, reject) => {
+ this.call(func,
+ val => resolve(this.#to_js(val)),
+ err => reject(this.#to_js(err)),
+ ...args);
+ })
+ }
+
+ car(x) { return this.#to_js(this.#instance.exports.car(x.obj)); }
+ cdr(x) { return this.#to_js(this.#instance.exports.cdr(x.obj)); }
+
+ vector_length(x) { return this.#instance.exports.vector_length(x.obj); }
+ vector_ref(x, i) {
+ return this.#to_js(this.#instance.exports.vector_ref(x.obj, i));
+ }
+
+ bytevector_length(x) {
+ return this.#instance.exports.bytevector_length(x.obj);
+ }
+ bytevector_ref(x, i) {
+ return this.#instance.exports.bytevector_ref(x.obj, i);
+ }
+
+ bitvector_length(x) {
+ return this.#instance.exports.bitvector_length(x.obj);
+ }
+ bitvector_ref(x, i) {
+ return this.#instance.exports.bitvector_ref(x.obj, i) == 1;
+ }
+
+ string_value(x) { return this.#instance.exports.string_value(x.obj); }
+ symbol_name(x) { return this.#instance.exports.symbol_name(x.obj); }
+ keyword_name(x) { return this.#instance.exports.keyword_name(x.obj); }
+}
+
+class SchemeTrapError extends Error {
+ constructor(tag, data) { super(); this.tag = tag; this.data = data; }
+ // FIXME: data is raw Scheme object; would need to be reflected to
+ // have a toString.
+ toString() { return `SchemeTrap(${this.tag}, <data>)`; }
+}
+
+function string_repr(str) {
+ // FIXME: Improve to match Scheme.
+ return '"' + str.replace(/(["\\])/g, '\\$1').replace(/\n/g, '\\n') + '"';
+}
+
+function flonum_to_string(f64) {
+ if (Object.is(f64, -0)) {
+ return '-0.0';
+ } else if (Number.isFinite(f64)) {
+ let repr = f64 + '';
+ return /^-?[0-9]+$/.test(repr) ? repr + '.0' : repr;
+ } else if (Number.isNaN(f64)) {
+ return '+nan.0';
+ } else {
+ return f64 < 0 ? '-inf.0' : '+inf.0';
+ }
+}
+
+let async_invoke = typeof queueMicrotask !== 'undefined'
+ ? queueMicrotask
+ : thunk => setTimeout(thunk, 0);
+function async_invoke_later(thunk, jiffies) {
+ setTimeout(thunk, jiffies / 1000);
+}
+
+let wtf8_helper;
+
+function wtf8_to_string(wtf8) {
+ let { as_iter, iter_next } = wtf8_helper.exports;
+ let codepoints = [];
+ let iter = as_iter(wtf8);
+ for (let cp = iter_next(iter); cp != -1; cp = iter_next(iter))
+ codepoints.push(cp);
+
+ // Passing too many codepoints can overflow the stack.
+ let maxcp = 100000;
+ if (codepoints.length <= maxcp) {
+ return String.fromCodePoint(...codepoints);
+ }
+
+ // For converting large strings, concatenate several smaller
+ // strings.
+ let substrings = [];
+ let end = 0;
+ for (let start = 0; start != codepoints.length; start = end) {
+ end = Math.min(start + maxcp, codepoints.length);
+ substrings.push(String.fromCodePoint(...codepoints.slice(start, end)));
+ }
+ return substrings.join('');
+}
+
+function string_to_wtf8(str) {
+ let { string_builder, builder_push_codepoint, finish_builder } =
+ wtf8_helper.exports;
+ let builder = string_builder()
+ for (let cp of str)
+ builder_push_codepoint(builder, cp.codePointAt(0));
+ return finish_builder(builder);
+}
+
+async function load_wtf8_helper_module(reflect_wasm_dir = '') {
+ if (wtf8_helper) return;
+ let wtf8_wasm = reflect_wasm_dir + "/wtf8.wasm";
+ let { module, instance } = await instantiate_streaming(wtf8_wasm);
+ wtf8_helper = instance;
+}
+
+class SchemeModule {
+ #instance;
+ #io_handler;
+ #debug_handler;
+ #ffi_handler;
+ static #rt = {
+ bignum_from_string(str) { return BigInt(str); },
+ bignum_from_i32(n) { return BigInt(n); },
+ bignum_from_i64(n) { return n; },
+ bignum_from_u64(n) { return n < 0n ? 0xffff_ffff_ffff_ffffn + (n + 1n) : n; },
+ bignum_is_i64(n) {
+ return -0x8000_0000_0000_0000n <= n && n <= 0x7FFF_FFFF_FFFF_FFFFn;
+ },
+ bignum_is_u64(n) {
+ return 0n <= n && n <= 0xFFFF_FFFF_FFFF_FFFFn;
+ },
+ // This truncates; see https://tc39.es/ecma262/#sec-tobigint64.
+ bignum_get_i64(n) { return n; },
+
+ bignum_add(a, b) { return BigInt(a) + BigInt(b) },
+ bignum_sub(a, b) { return BigInt(a) - BigInt(b) },
+ bignum_mul(a, b) { return BigInt(a) * BigInt(b) },
+ bignum_lsh(a, b) { return BigInt(a) << BigInt(b) },
+ bignum_rsh(a, b) { return BigInt(a) >> BigInt(b) },
+ bignum_quo(a, b) { return BigInt(a) / BigInt(b) },
+ bignum_rem(a, b) { return BigInt(a) % BigInt(b) },
+ bignum_mod(a, b) {
+ let r = BigInt(a) % BigInt(b);
+ if ((b > 0n && r < 0n) || (b < 0n && r > 0n)) {
+ return b + r;
+ } else {
+ return r;
+ }
+ },
+ bignum_gcd(a, b) {
+ a = BigInt(a);
+ b = BigInt(b);
+ if (a < 0n) { a = -a; }
+ if (b < 0n) { b = -b; }
+ if (a == 0n) { return b; }
+ if (b == 0n) { return a; }
+
+ let r;
+ while (b != 0n) {
+ r = a % b;
+ a = b;
+ b = r;
+ }
+ return a;
+ },
+
+ bignum_logand(a, b) { return BigInt(a) & BigInt(b); },
+ bignum_logior(a, b) { return BigInt(a) | BigInt(b); },
+ bignum_logxor(a, b) { return BigInt(a) ^ BigInt(b); },
+ bignum_logsub(a, b) { return BigInt(a) & (~ BigInt(b)); },
+
+ bignum_lt(a, b) { return a < b; },
+ bignum_le(a, b) { return a <= b; },
+ bignum_eq(a, b) { return a == b; },
+
+ bignum_to_f64(n) { return Number(n); },
+
+ f64_is_nan(n) { return Number.isNaN(n); },
+ f64_is_infinite(n) { return !Number.isFinite(n); },
+
+ flonum_to_string,
+
+ string_upcase: Function.call.bind(String.prototype.toUpperCase),
+ string_downcase: Function.call.bind(String.prototype.toLowerCase),
+
+ make_weak_map() { return new WeakMap; },
+ weak_map_get(map, k, fail) {
+ const val = map.get(k);
+ return val === undefined ? fail: val;
+ },
+ weak_map_set(map, k, v) { return map.set(k, v); },
+ weak_map_delete(map, k) { return map.delete(k); },
+
+ fsqrt: Math.sqrt,
+ fsin: Math.sin,
+ fcos: Math.cos,
+ ftan: Math.tan,
+ fasin: Math.asin,
+ facos: Math.acos,
+ fatan: Math.atan,
+ fatan2: Math.atan2,
+ flog: Math.log,
+ fexp: Math.exp,
+
+ jiffies_per_second() { return 1000000; },
+ current_jiffy() { return performance.now() * 1000; },
+ current_second() { return Date.now() / 1000; },
+
+ async_invoke,
+ async_invoke_later,
+ promise_on_completed(p, kt, kf) { p.then(kt, kf); },
+ promise_complete(callback, val) { callback(val); },
+
+ // Wrap in functions to allow for lazy loading of the wtf8
+ // module.
+ wtf8_to_string(wtf8) { return wtf8_to_string(wtf8); },
+ string_to_wtf8(str) { return string_to_wtf8(str); },
+
+ die(tag, data) { throw new SchemeTrapError(tag, data); }
+ };
+
+ constructor(instance) {
+ this.#instance = instance;
+ let open_file_error = (filename) => {
+ throw new Error('No file system access');
+ };
+ if (typeof printErr === 'function') { // v8/sm dev console
+ // On the console, try to use 'write' (v8) or 'putstr' (sm),
+ // as these don't add an extraneous newline. Unfortunately
+ // JSC doesn't have a printer that doesn't add a newline.
+ let write_no_newline =
+ typeof write === 'function' ? write
+ : typeof putstr === 'function' ? putstr : print;
+ // Use readline when available. v8 strips newlines so
+ // we need to add them back.
+ let read_stdin =
+ typeof readline == 'function' ? () => {
+ let line = readline();
+ if (line) {
+ return `${line}\n`;
+ } else {
+ return '\n';
+ }
+ }: () => '';
+ this.#io_handler = {
+ write_stdout: write_no_newline,
+ write_stderr: printErr,
+ read_stdin,
+ file_exists: (filename) => false,
+ open_input_file: open_file_error,
+ open_output_file: open_file_error,
+ close_file: () => undefined,
+ read_file: (handle, length) => 0,
+ write_file: (handle, length) => 0,
+ seek_file: (handle, offset, whence) => -1,
+ file_random_access: (handle) => false,
+ file_buffer_size: (handle) => 0,
+ file_buffer_ref: (handle, i) => 0,
+ file_buffer_set: (handle, i, x) => undefined,
+ delete_file: (filename) => undefined
+ };
+ } else if (typeof window !== 'undefined') { // web browser
+ this.#io_handler = {
+ write_stdout: console.log,
+ write_stderr: console.error,
+ read_stdin: () => '',
+ file_exists: (filename) => false,
+ open_input_file: open_file_error,
+ open_output_file: open_file_error,
+ close_file: () => undefined,
+ read_file: (handle, length) => 0,
+ write_file: (handle, length) => 0,
+ seek_file: (handle, offset, whence) => -1,
+ file_random_access: (handle) => false,
+ file_buffer_size: (handle) => 0,
+ file_buffer_ref: (handle, i) => 0,
+ file_buffer_set: (handle, i, x) => undefined,
+ delete_file: (filename) => undefined
+ };
+ } else { // nodejs
+ const fs = require('fs');
+ const process = require('process');
+ const bufLength = 1024;
+ const stdinBuf = Buffer.alloc(bufLength);
+ const SEEK_SET = 0, SEEK_CUR = 1, SEEK_END = 2;
+ this.#io_handler = {
+ write_stdout: console.log,
+ write_stderr: console.error,
+ read_stdin: () => {
+ let n = fs.readSync(process.stdin.fd, stdinBuf, 0, stdinBuf.length);
+ return stdinBuf.toString('utf8', 0, n);
+ },
+ file_exists: fs.existsSync.bind(fs),
+ open_input_file: (filename) => {
+ let fd = fs.openSync(filename, 'r');
+ return {
+ fd,
+ buf: Buffer.alloc(bufLength),
+ pos: 0
+ };
+ },
+ open_output_file: (filename) => {
+ let fd = fs.openSync(filename, 'w');
+ return {
+ fd,
+ buf: Buffer.alloc(bufLength),
+ pos: 0
+ };
+ },
+ close_file: (handle) => {
+ fs.closeSync(handle.fd);
+ },
+ read_file: (handle, count) => {
+ const n = fs.readSync(handle.fd, handle.buf, 0, count, handle.pos);
+ handle.pos += n;
+ return n;
+ },
+ write_file: (handle, count) => {
+ const n = fs.writeSync(handle.fd, handle.buf, 0, count, handle.pos);
+ handle.pos += n;
+ return n;
+ },
+ seek_file: (handle, offset, whence) => {
+ // There doesn't seem to be a way to ask NodeJS if
+ // a position is valid or not.
+ if (whence == SEEK_SET) {
+ handle.pos = offset;
+ return handle.pos;
+ } else if (whence == SEEK_CUR) {
+ handle.pos += offset;
+ return handle.pos;
+ }
+
+ // SEEK_END not supported.
+ return -1;
+ },
+ file_random_access: (handle) => {
+ return true;
+ },
+ file_buffer_size: (handle) => {
+ return handle.buf.length;
+ },
+ file_buffer_ref: (handle, i) => {
+ return handle.buf[i];
+ },
+ file_buffer_set: (handle, i, x) => {
+ handle.buf[i] = x;
+ },
+ delete_file: fs.rmSync.bind(fs)
+ };
+ }
+ this.#debug_handler = {
+ debug_str(x) { console.log(`debug: ${x}`); },
+ debug_str_i32(x, y) { console.log(`debug: ${x}: ${y}`); },
+ debug_str_scm(x, y) { console.log(`debug: ${x}: #<scm>`); },
+ };
+ }
+ static async fetch_and_instantiate(path, { abi, reflect_wasm_dir = '.',
+ user_imports = {} }) {
+ await load_wtf8_helper_module(reflect_wasm_dir);
+ let io = {
+ write_stdout(str) { mod.#io_handler.write_stdout(str); },
+ write_stderr(str) { mod.#io_handler.write_stderr(str); },
+ read_stdin() { return mod.#io_handler.read_stdin(); },
+ file_exists(filename) { return mod.#io_handler.file_exists(filename); },
+ open_input_file(filename) { return mod.#io_handler.open_input_file(filename); },
+ open_output_file(filename) { return mod.#io_handler.open_output_file(filename); },
+ close_file(handle) { mod.#io_handler.close_file(handle); },
+ read_file(handle, length) { return mod.#io_handler.read_file(handle, length); },
+ write_file(handle, length) { return mod.#io_handler.write_file(handle, length); },
+ seek_file(handle, offset, whence) { return mod.#io_handler.seek_file(handle, offset, whence); },
+ file_random_access(handle) { return mod.#io_handler.file_random_access(handle); },
+ file_buffer_size(handle) { return mod.#io_handler.file_buffer_size(handle); },
+ file_buffer_ref(handle, i) { return mod.#io_handler.file_buffer_ref(handle, i); },
+ file_buffer_set(handle, i, x) { return mod.#io_handler.file_buffer_set(handle, i, x); },
+ delete_file(filename) { mod.#io_handler.delete_file(filename); }
+ };
+ let debug = {
+ debug_str(x) { mod.#debug_handler.debug_str(x); },
+ debug_str_i32(x, y) { mod.#debug_handler.debug_str_i32(x, y); },
+ debug_str_scm(x, y) { mod.#debug_handler.debug_str_scm(x, y); },
+ }
+ let ffi = {
+ procedure_to_extern(proc) {
+ return mod.#ffi_handler.procedure_to_extern(proc);
+ }
+ };
+ let imports = {
+ rt: SchemeModule.#rt,
+ abi, debug, io, ffi, ...user_imports
+ };
+ let { module, instance } = await instantiate_streaming(path, imports);
+ let mod = new SchemeModule(instance);
+ return mod;
+ }
+ set_io_handler(h) { this.#io_handler = h; }
+ set_debug_handler(h) { this.#debug_handler = h; }
+ set_ffi_handler(h) { this.#ffi_handler = h; }
+ all_exports() { return this.#instance.exports; }
+ exported_abi() {
+ let abi = {}
+ for (let [k, v] of Object.entries(this.all_exports())) {
+ if (k.startsWith("$"))
+ abi[k] = v;
+ }
+ return abi;
+ }
+ exports() {
+ let ret = {}
+ for (let [k, v] of Object.entries(this.all_exports())) {
+ if (!k.startsWith("$"))
+ ret[k] = v;
+ }
+ return ret;
+ }
+ get_export(name) {
+ if (name in this.all_exports())
+ return this.all_exports()[name];
+ throw new Error(`unknown export: ${name}`)
+ }
+ async reflect(opts = {}) {
+ return await Scheme.reflect(this.exported_abi(), opts);
+ }
+}
+
+function repr(obj) {
+ if (obj instanceof HeapObject)
+ return obj.repr();
+ if (typeof obj === 'boolean')
+ return obj ? '#t' : '#f';
+ if (typeof obj === 'number')
+ return flonum_to_string(obj);
+ if (typeof obj === 'string')
+ return string_repr(obj);
+ return obj + '';
+}
diff --git a/chapter-7/hoot/reflect.wasm b/chapter-7/hoot/reflect.wasm
new file mode 100644
index 0000000..770c94c
--- /dev/null
+++ b/chapter-7/hoot/reflect.wasm
Binary files differ
diff --git a/chapter-7/hoot/wtf8.wasm b/chapter-7/hoot/wtf8.wasm
new file mode 100644
index 0000000..ca1079d
--- /dev/null
+++ b/chapter-7/hoot/wtf8.wasm
Binary files differ
diff --git a/chapter-7/index.html b/chapter-7/index.html
new file mode 100644
index 0000000..e5c4372
--- /dev/null
+++ b/chapter-7/index.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<html>
+ <head>
+ <title>FRP color picker</title>
+ <link rel="stylesheet" type="text/css" href="propagators.css"/>
+ <script type="text/javascript" src="hoot/reflect.js"></script>
+ <script type="text/javascript" src="propagators.js"></script>
+ </head>
+ <body>
+ <article id="wasm-error" hidden="true">
+ <h1>Uh oh!</h1>
+ <p>
+ A browser with Wasm GC and tail call support is required for
+ this demo.
+ </p>
+ <p>
+ We recommend using either Firefox or Chrome.
+ </p>
+ <p>
+ Safari is currently unsupported. Likewise, <emph>all browsers</emph> on
+ iOS are unsupported, as they are all secretly Safari under the
+ hood.
+ </p>
+ </article>
+ </body>
+</html>
diff --git a/chapter-7/manifest.scm b/chapter-7/manifest.scm
new file mode 100644
index 0000000..237372a
--- /dev/null
+++ b/chapter-7/manifest.scm
@@ -0,0 +1,24 @@
+(use-modules (guix git-download)
+ (guix packages)
+ (gnu packages base)
+ (gnu packages guile)
+ (gnu packages guile-xyz))
+
+(define guile-hoot-next
+ (let ((commit "addbcd33158265a6c00e87aeb89d9c20f57bce1e")
+ (revision "1"))
+ (package
+ (inherit guile-hoot)
+ (version (git-version "0.4.1" revision commit))
+ (source (origin
+ (method git-fetch)
+ (uri (git-reference
+ (url "https://gitlab.com/spritely/guile-hoot.git")
+ (commit commit)))
+ (file-name (git-file-name "guile-hoot" version))
+ (sha256
+ (base32 "1zv8w9pawr3wajlcr862x21198x421fa47qbfkblnidiknfgs7sa"))))
+ (arguments
+ '(#:tests? #f)))))
+
+(packages->manifest (list guile-next guile-hoot-next gnu-make))
diff --git a/chapter-7/propagators.css b/chapter-7/propagators.css
new file mode 100644
index 0000000..1b803e2
--- /dev/null
+++ b/chapter-7/propagators.css
@@ -0,0 +1,38 @@
+body {
+ font-family: sans;
+ background-color: #fbfbfb;
+ margin: auto;
+ max-width: 20em;
+}
+
+h1 {
+ text-align: center;
+}
+
+.preview {
+ width: 50%;
+ margin-left: auto;
+ margin-right: auto;
+}
+
+.hex {
+ text-align: center;
+ margin-top: 0.5em;
+}
+
+fieldset {
+ margin-bottom: 1em;
+ margin-top: 1em;
+}
+
+.color-block {
+ width: 100%;
+ aspect-ratio: 1;
+ border: 1px black solid;
+}
+
+.slider {
+ display: grid;
+ grid-template-columns: 35% max-content;
+ grip-gap: 1em;
+}
diff --git a/chapter-7/propagators.js b/chapter-7/propagators.js
new file mode 100644
index 0000000..fe0034a
--- /dev/null
+++ b/chapter-7/propagators.js
@@ -0,0 +1,30 @@
+window.addEventListener("load", async () => {
+ try {
+ await Scheme.load_main("propagators.wasm", {
+ reflect_wasm_dir: "hoot",
+ user_imports: {
+ window: {
+ setTimeout: setTimeout
+ },
+ document: {
+ makeTextNode: Document.prototype.createTextNode.bind(document),
+ makeElement: Document.prototype.createElement.bind(document),
+ body: () => document.body,
+ },
+ element: {
+ appendChild: (parent, child) => parent.appendChild(child),
+ setAttribute: (elem, attr, value) => elem.setAttribute(attr, value),
+ getValue: (elem) => elem.value,
+ setValue: (elem, val) => elem.value = val,
+ replaceWith: (oldElem, newElem) => oldElem.replaceWith(newElem),
+ addEventListener: (elem, name, f) => elem.addEventListener(name, f)
+ },
+ }
+ });
+ } catch(e) {
+ if(e instanceof WebAssembly.CompileError) {
+ document.getElementById("wasm-error").hidden = false;
+ }
+ throw e;
+ }
+});
diff --git a/chapter-7/propagators.scm b/chapter-7/propagators.scm
new file mode 100644
index 0000000..c3d0cc4
--- /dev/null
+++ b/chapter-7/propagators.scm
@@ -0,0 +1,659 @@
+;;; Copyright © 2024 David Thompson <dthompson2@worcester.edu>
+;;;
+;;; This program is free software: you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation, either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; This program is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with this program. If not, see
+;;; <http://www.gnu.org/licenses/>.
+(use-modules (ice-9 match)
+ (srfi srfi-9)
+ (srfi srfi-9 gnu)
+ ((hoot hashtables) #:select (make-weak-key-hashtable
+ weak-key-hashtable-ref
+ weak-key-hashtable-set!))
+ ((hoot lists) #:select (fold))
+ ((hoot numbers) #:select (truncate))
+ (hoot ffi))
+
+(define-foreign timeout
+ "window" "setTimeout"
+ (ref extern) f64 -> i32)
+
+(define-foreign document-body
+ "document" "body"
+ -> (ref null extern))
+
+(define-foreign make-text-node
+ "document" "makeTextNode"
+ (ref string) -> (ref extern))
+
+(define-foreign make-element
+ "document" "makeElement"
+ (ref string) -> (ref extern))
+
+(define-foreign append-child!
+ "element" "appendChild"
+ (ref extern) (ref extern) -> (ref extern))
+
+(define-foreign attribute-set!
+ "element" "setAttribute"
+ (ref extern) (ref string) (ref string) -> none)
+
+(define-foreign value
+ "element" "getValue"
+ (ref extern) -> (ref string))
+
+(define-foreign set-value!
+ "element" "setValue"
+ (ref extern) (ref string) -> none)
+
+(define-foreign add-event-listener!
+ "element" "addEventListener"
+ (ref extern) (ref string) (ref extern) -> none)
+
+(define-foreign replace-with!
+ "element" "replaceWith"
+ (ref extern) (ref extern) -> none)
+
+(define (lset-adjoin = list . rest)
+ (define pred
+ (if (or (eq? = eq?) (eq? = eqv?))
+ =
+ (lambda (x y) (= y x))))
+ (let lp ((ans list) (rest rest))
+ (match rest
+ (() ans)
+ ((x . rest*)
+ (lp (if (member x ans pred)
+ ans
+ (cons x ans))
+ rest*)))))
+
+(define (any pred lst)
+ (let lp ((lst lst))
+ (match lst
+ (() #f)
+ ((x . rest)
+ (or (pred x) (lp rest))))))
+
+(define (every pred lst)
+ (let lp ((lst lst))
+ (match lst
+ (() #t)
+ ((x . rest)
+ (and (pred x) (lp rest))))))
+
+(define procedure->external*
+ (let ((cache (make-weak-key-hashtable)))
+ (lambda (proc)
+ (or (weak-key-hashtable-ref cache proc)
+ (let ((extern (procedure->external proc)))
+ (weak-key-hashtable-set! cache proc extern)
+ extern)))))
+(define (queue-task! thunk)
+ (timeout (procedure->external* thunk) 0.0))
+
+(define-record-type <nothing>
+ (make-nothing)
+ %nothing?)
+(define (print-nothing nothing port)
+ (display "#<nothing>" port))
+(set-record-type-printer! <nothing> print-nothing)
+(define nothing (make-nothing))
+(define (nothing? x) (eq? x nothing))
+
+(define-record-type <contradiction>
+ (make-contradiction details)
+ contradiction?
+ (details contradiction-details))
+
+(define (print-contradiction contradiction port)
+ (format port "#<contradiction ~a>"
+ (contradiction-details contradiction)))
+(set-record-type-printer! <contradiction> print-contradiction)
+
+(define contradiction (make-contradiction nothing))
+
+(define-record-type <relations>
+ (%make-relations name parent children)
+ relations?
+ (name relations-name)
+ (parent relations-parent)
+ (children relations-children set-relations-children!))
+
+(define (print-relations relations port)
+ (match relations
+ (($ <relations> name parent children)
+ (format port "#<relations ~a ↑ ~a ↓ ~a>"
+ name parent children))))
+(set-record-type-printer! <relations> print-relations)
+
+(define current-parent (make-parameter #f))
+
+(define (make-relations name)
+ (%make-relations name (current-parent) '()))
+
+(define (add-child! parent child)
+ (when parent
+ (set-relations-children! parent (cons child (relations-children parent)))))
+
+(define-record-type <cell>
+ (%make-cell relations neighbors content strongest
+ equivalent? merge find-strongest handle-contradiction)
+ cell?
+ (relations cell-relations)
+ (neighbors cell-neighbors set-cell-neighbors!)
+ (content cell-content set-cell-content!)
+ (strongest cell-strongest set-cell-strongest!)
+ ;; Dispatch table:
+ (equivalent? cell-equivalent?)
+ (merge cell-merge)
+ (find-strongest cell-find-strongest)
+ (handle-contradiction cell-handle-contradiction))
+
+(define (print-cell cell port)
+ (match cell
+ (($ <cell> ($ <relations> name) _ _ strongest)
+ (display "#<cell " port)
+ (display name port)
+ (display " " port)
+ (display strongest port)
+ (display ">" port))))
+(set-record-type-printer! <cell> print-cell)
+
+(define-record-type <propagator>
+ (%make-propagator relations inputs outputs activate)
+ propagator?
+ (relations propagator-relations)
+ (inputs propagator-inputs)
+ (outputs propagator-outputs)
+ (activate propagator-activate))
+
+(define (print-propagator propagator port)
+ (match propagator
+ (($ <propagator> ($ <relations> name) inputs outputs)
+ (display "#<propagator " port)
+ (display name port)
+ (display " " port)
+ (display inputs port)
+ (display " -> " port)
+ (display outputs port)
+ (display ">" port))))
+(set-record-type-printer! <propagator> print-propagator)
+
+(define default-equivalent? equal?)
+;; But what about partial information???
+(define (default-merge old new) new)
+(define (default-find-strongest content) content)
+(define (default-handle-contradiction cell) (values))
+
+(define* (make-cell name #:key
+ (equivalent? default-equivalent?)
+ (merge default-merge)
+ (find-strongest default-find-strongest)
+ (handle-contradiction default-handle-contradiction))
+ (let ((cell (%make-cell (make-relations name) '() nothing nothing
+ equivalent? merge find-strongest
+ handle-contradiction)))
+ (add-child! (current-parent) cell)
+ cell))
+
+(define (cell-name cell)
+ (relations-name (cell-relations cell)))
+
+(define (add-cell-neighbor! cell neighbor)
+ (set-cell-neighbors! cell (lset-adjoin eq? (cell-neighbors cell) neighbor)))
+
+(define (add-cell-content! cell new)
+ (match cell
+ (($ <cell> _ neighbors content strongest equivalent? merge
+ find-strongest handle-contradiction)
+ (let ((content* (merge content new)))
+ (set-cell-content! cell content*)
+ (let ((strongest* (find-strongest content*)))
+ (cond
+ ;; New strongest value is equivalent to the old one. No need
+ ;; to alert propagators.
+ ((equivalent? strongest strongest*)
+ (set-cell-strongest! cell strongest*))
+ ;; Uh oh, a contradiction! Call handler.
+ ((contradiction? strongest*)
+ (set-cell-strongest! cell strongest*)
+ (handle-contradiction cell))
+ ;; Strongest value has changed. Alert the propagators!
+ (else
+ (set-cell-strongest! cell strongest*)
+ (for-each alert-propagator! neighbors))))))))
+
+(define (alert-propagator! propagator)
+ (queue-task! (propagator-activate propagator)))
+
+(define (make-propagator name inputs outputs activate)
+ (let ((propagator (%make-propagator (make-relations name)
+ inputs outputs activate)))
+ (add-child! (current-parent) propagator)
+ (for-each (lambda (cell)
+ (add-cell-neighbor! cell propagator))
+ inputs)
+ (alert-propagator! propagator)
+ propagator))
+
+(define (unusable-value? x)
+ (or (nothing? x) (contradiction? x)))
+
+(define (primitive-propagator name f)
+ (match-lambda*
+ ((inputs ... output)
+ (define (activate)
+ (let ((args (map cell-strongest inputs)))
+ (unless (any unusable-value? args)
+ (add-cell-content! output (apply f args)))))
+ (make-propagator name inputs (list output) activate))))
+
+(define (compound-propagator name inputs outputs build)
+ (let ((built? #f))
+ (define (maybe-build)
+ (unless (or built?
+ (and (not (null? inputs))
+ (every unusable-value? (map cell-strongest inputs))))
+ (parameterize ((current-parent (propagator-relations propagator)))
+ (build)
+ (set! built? #t))))
+ (define propagator (make-propagator name inputs outputs maybe-build))
+ propagator))
+
+(define (constraint-propagator name cells build)
+ (compound-propagator name cells cells build))
+
+(define-record-type <reactive-id>
+ (%make-reactive-id name clock)
+ reactive-id?
+ (name reactive-id-name)
+ (clock reactive-id-clock set-reactive-id-clock!))
+
+(define (print-reactive-id id port)
+ (display "#<reactive-id " port)
+ (display (reactive-id-name id) port)
+ (display ">" port))
+(set-record-type-printer! <reactive-id> print-reactive-id)
+
+(define (make-reactive-id name)
+ (%make-reactive-id name 0))
+
+(define (reactive-id-tick! id)
+ (let ((t (1+ (reactive-id-clock id))))
+ (set-reactive-id-clock! id t)
+ `((,id . ,t))))
+
+;; Partial value structure for FRP
+(define-record-type <ephemeral>
+ (make-ephemeral value timestamps)
+ ephemeral?
+ (value ephemeral-value)
+ ;; Association list mapping identity -> time
+ (timestamps ephemeral-timestamps))
+
+(define (ephemeral-fresher? a b)
+ (let ((b-inputs (ephemeral-timestamps b)))
+ (let lp ((a-inputs (ephemeral-timestamps a)))
+ (match a-inputs
+ (() #t)
+ (((key . a-time) . rest)
+ (match (assq-ref b-inputs key)
+ (#f (lp rest))
+ (b-time
+ (and (> a-time b-time)
+ (lp rest)))))))))
+
+(define (merge-ephemeral-timestamps ephemerals)
+ (define (adjoin-keys alist keys)
+ (fold (lambda (key+value keys)
+ (match key+value
+ ((key . _)
+ (lset-adjoin eq? keys key))))
+ keys alist))
+ (define (check-timestamps id)
+ (let lp ((ephemerals ephemerals) (t #f))
+ (match ephemerals
+ (() t)
+ ((($ <ephemeral> _ timestamps) . rest)
+ (match (assq-ref timestamps id)
+ ;; No timestamp for this id in this ephemeral. Continue.
+ (#f (lp rest t))
+ (t*
+ (if t
+ ;; If timestamps don't match then we have a mix of
+ ;; fresh and stale values, so return #f. Otherwise,
+ ;; continue.
+ (and (= t t*) (lp rest t))
+ ;; Initialize timestamp and continue.
+ (lp rest t*))))))))
+ ;; Build a set of all reactive identifiers across all ephemerals.
+ (let ((ids (fold (lambda (ephemeral ids)
+ (adjoin-keys (ephemeral-timestamps ephemeral) ids))
+ '() ephemerals)))
+ (let lp ((ids ids) (timestamps '()))
+ (match ids
+ (() timestamps)
+ ((id . rest)
+ ;; Check for consistent timestamps. If they are consistent
+ ;; then add it to the alist and continue. Otherwise, return
+ ;; #f.
+ (let ((t (check-timestamps id)))
+ (and t (lp rest (cons (cons id t) timestamps)))))))))
+
+(define (merge-ephemerals old new)
+ (cond
+ ((nothing? old) new)
+ ((nothing? new) old)
+ ((ephemeral-fresher? new old) new)
+ (else old)))
+
+(define (ephemeral-wrap proc)
+ (match-lambda*
+ ((and ephemerals (($ <ephemeral> args) ...))
+ (match (merge-ephemeral-timestamps ephemerals)
+ (#f nothing)
+ (timestamps (make-ephemeral (apply proc args) timestamps))))))
+
+(define* (primitive-reactive-propagator name proc)
+ (primitive-propagator name (ephemeral-wrap proc)))
+
+(define-syntax-rule (define-primitive-reactive-propagator name proc)
+ (define name (primitive-reactive-propagator 'name proc)))
+
+(define (r:attribute input elem attr)
+ (let ((attr (symbol->string attr)))
+ (define (activate)
+ (match (cell-strongest input)
+ (($ <ephemeral> val)
+ (attribute-set! elem attr (obj->string val)))
+ ;; Ignore unusable values.
+ (_ (values))))
+ (make-propagator 'r:attribute (list input) '() activate)))
+
+(define-record-type <binding>
+ (make-binding id cell default group)
+ binding?
+ (id binding-id)
+ (cell binding-cell)
+ (default binding-default)
+ (group binding-group))
+
+(define* (binding id cell #:key (default nothing) (group '()))
+ (make-binding id cell default group))
+
+(define (obj->string obj)
+ (if (string? obj)
+ obj
+ (call-with-output-string
+ (lambda (port)
+ (write obj port)))))
+
+(define (string->obj str)
+ (call-with-input-string str read))
+
+(define* (r:binding binding elem)
+ (match binding
+ (($ <binding> id cell default group)
+ (define (update new)
+ (unless (nothing? new)
+ (let ((timestamp (reactive-id-tick! id)))
+ (add-cell-content! cell (make-ephemeral new timestamp))
+ ;; Freshen timestamps for all cells in the same group.
+ (for-each (lambda (other)
+ (unless (eq? other cell)
+ (match (cell-strongest other)
+ (($ <ephemeral> val)
+ (add-cell-content! other (make-ephemeral val timestamp)))
+ (_ #f))))
+ group))))
+ ;; Sync the element's value with the cell's value.
+ (define (activate)
+ (match (cell-strongest cell)
+ (($ <ephemeral> val)
+ (set-value! elem (obj->string val)))
+ (_ (values))))
+ ;; Initialize element value with the default value.
+ (update default)
+ ;; Sync the cell's value with the element's value.
+ (add-event-listener! elem "input"
+ (procedure->external
+ (lambda (event)
+ (update (string->obj (value elem))))))
+ (make-propagator 'r:binding (list cell) '() activate))))
+
+(define (cell->elem cell)
+ (let ((exp (cell-strongest cell)))
+ (if (unusable-value? exp)
+ (make-text-node "")
+ (sxml->dom exp))))
+
+(define (sxml->dom exp)
+ (match exp
+ ;; The simple case: a string representing a text node.
+ ((? string? str)
+ (make-text-node str))
+ ((? number? num)
+ (make-text-node (number->string num)))
+ ;; A cell containing SXML (or nothing)
+ ((? cell? cell)
+ (let ((elem (cell->elem cell)))
+ (r:dom cell elem)
+ elem))
+ ;; An element tree. The first item is the HTML tag.
+ (((? symbol? tag) . body)
+ ;; Create a new element with the given tag.
+ (let ((elem (make-element (symbol->string tag))))
+ (define (add-children children)
+ ;; Recursively call sxml->dom for each child node and
+ ;; append it to elem.
+ (for-each (lambda (child)
+ (append-child! elem (sxml->dom child)))
+ children))
+ (match body
+ ((('@ . attrs) . children)
+ (for-each (lambda (attr)
+ (match attr
+ (((? symbol? name) (? string? val))
+ (attribute-set! elem
+ (symbol->string name)
+ val))
+ (((? symbol? name) (? number? val))
+ (attribute-set! elem
+ (symbol->string name)
+ (number->string val)))
+ (((? symbol? name) (? cell? cell))
+ (r:attribute cell elem name))
+ ;; The value attribute is special and can be
+ ;; used to setup a 2-way data binding.
+ (('value (? binding? binding))
+ (r:binding binding elem))))
+ attrs)
+ (add-children children))
+ (children (add-children children)))
+ elem))))
+
+(define (r:dom input elem)
+ (define (activate)
+ (match (cell-strongest input)
+ (($ <ephemeral> exp)
+ (let ((new (sxml->dom exp)))
+ (replace-with! elem new)
+ (set! elem new)))
+ (_ (values))))
+ (make-propagator 'dom (list input) '() activate))
+
+(define-record-type <rgb-color>
+ (rgb-color r g b)
+ rgb-color?
+ (r rgb-color-r)
+ (g rgb-color-g)
+ (b rgb-color-b))
+
+(define-record-type <hsv-color>
+ (hsv-color h s v)
+ hsv-color?
+ (h hsv-color-h)
+ (s hsv-color-s)
+ (v hsv-color-v))
+
+(define (assert-real x)
+ (unless (real? x)
+ (error "expected real number" x)))
+
+(define (fmod x y)
+ (assert-real x)
+ (assert-real y)
+ (- x (* (truncate (/ x y)) y)))
+
+(define (rgb->hsv rgb)
+ (match rgb
+ (($ <rgb-color> r g b)
+ (let* ((cmax (max r g b))
+ (cmin (min r g b))
+ (delta (- cmax cmin)))
+ (hsv-color (cond
+ ((= delta 0.0) 0.0)
+ ((= cmax r)
+ (let ((h (* 60.0 (fmod (/ (- g b) delta) 6.0))))
+ (if (< h 0.0) (+ h 360.0) h)))
+ ((= cmax g) (* 60.0 (+ (/ (- b r) delta) 2.0)))
+ ((= cmax b) (* 60.0 (+ (/ (- r g) delta) 4.0))))
+ (if (= cmax 0.0)
+ 0.0
+ (/ delta cmax))
+ cmax)))))
+
+(define (hsv->rgb hsv)
+ (match hsv
+ (($ <hsv-color> h s v)
+ (let* ((h' (/ h 60.0))
+ (c (* v s))
+ (x (* c (- 1.0 (abs (- (fmod h' 2.0) 1.0)))))
+ (m (- v c)))
+ (define-values (r' g' b')
+ (cond
+ ((<= 0.0 h 60.0) (values c x 0.0))
+ ((<= h 120.0) (values x c 0.0))
+ ((<= h 180.0) (values 0.0 c x))
+ ((<= h 240.0) (values 0.0 x c))
+ ((<= h 300.0) (values x 0.0 c))
+ ((<= h 360.0) (values c 0.0 x))))
+ (rgb-color (+ r' m) (+ g' m) (+ b' m))))))
+
+(define (uniform->byte x)
+ (inexact->exact (round (* x 255.0))))
+
+(define (rgb->int rgb)
+ (match rgb
+ (($ <rgb-color> r g b)
+ (+ (* (uniform->byte r) (ash 1 16))
+ (* (uniform->byte g) (ash 1 8))
+ (uniform->byte b)))))
+
+(define (rgb->hex-string rgb)
+ (list->string
+ (cons #\#
+ (let lp ((i 0) (n (rgb->int rgb)) (out '()))
+ (if (= i 6)
+ out
+ (lp (1+ i) (ash n -4)
+ (cons (integer->char
+ (let ((digit (logand n 15)))
+ (+ (if (< digit 10)
+ (char->integer #\0)
+ (- (char->integer #\a) 10))
+ digit)))
+ out)))))))
+
+(define (rgb-hex->style hex)
+ (string-append "background-color: " hex ";"))
+
+(define-primitive-reactive-propagator r:rgb-color rgb-color)
+(define-primitive-reactive-propagator r:rgb-color-r rgb-color-r)
+(define-primitive-reactive-propagator r:rgb-color-g rgb-color-g)
+(define-primitive-reactive-propagator r:rgb-color-b rgb-color-b)
+(define-primitive-reactive-propagator r:hsv-color hsv-color)
+(define-primitive-reactive-propagator r:hsv-color-h hsv-color-h)
+(define-primitive-reactive-propagator r:hsv-color-s hsv-color-s)
+(define-primitive-reactive-propagator r:hsv-color-v hsv-color-v)
+(define-primitive-reactive-propagator r:rgb->hsv rgb->hsv)
+(define-primitive-reactive-propagator r:hsv->rgb hsv->rgb)
+(define-primitive-reactive-propagator r:rgb->hex-string rgb->hex-string)
+(define-primitive-reactive-propagator r:rgb-hex->style rgb-hex->style)
+
+(define (r:components<->rgb r g b rgb)
+ (define (build)
+ (r:rgb-color r g b rgb)
+ (r:rgb-color-r rgb r)
+ (r:rgb-color-g rgb g)
+ (r:rgb-color-b rgb b))
+ (constraint-propagator 'r:components<->rgb (list r g b rgb) build))
+
+(define (r:components<->hsv h s v hsv)
+ (define (build)
+ (r:hsv-color h s v hsv)
+ (r:hsv-color-h hsv h)
+ (r:hsv-color-s hsv s)
+ (r:hsv-color-v hsv v))
+ (constraint-propagator 'r:components<->hsv (list h s v hsv) build))
+
+(define (r:rgb<->hsv rgb hsv)
+ (define (build)
+ (r:rgb->hsv rgb hsv)
+ (r:hsv->rgb hsv rgb))
+ (constraint-propagator 'r:rgb<->hsv (list rgb hsv) build))
+
+(define (render exp)
+ (append-child! (document-body) (sxml->dom exp)))
+
+(define* (slider id name min max default #:optional (step "any"))
+ `(div (@ (class "slider"))
+ (label (@ (for ,id)) ,name)
+ (input (@ (id ,id) (type "range")
+ (min ,min) (max ,max) (step ,step)
+ (value ,default)))))
+
+(define (uslider id name default) ; [0,1] slider
+ (slider id name 0 1 default))
+
+(define-syntax-rule (with-cells (name ...) body . body*)
+ (let ((name (make-cell 'name #:merge merge-ephemerals)) ...) body . body*))
+
+(with-cells (r g b rgb h s v hsv hex style)
+ (define color (make-reactive-id 'color))
+ (define rgb-group (list r g b))
+ (define hsv-group (list h s v))
+ (r:components<->rgb r g b rgb)
+ (r:components<->hsv h s v hsv)
+ (r:rgb<->hsv rgb hsv)
+ (r:rgb->hex-string rgb hex)
+ (r:rgb-hex->style hex style)
+ (render
+ `(div
+ (h1 "Color Picker")
+ (div (@ (class "preview"))
+ (div (@ (class "color-block") (style ,style)))
+ (div (@ (class "hex")) ,hex))
+ (fieldset
+ (legend "RGB")
+ ,(uslider "red" "Red"
+ (binding color r #:default 1.0 #:group rgb-group))
+ ,(uslider "green" "Green"
+ (binding color g #:default 0.0 #:group rgb-group))
+ ,(uslider "blue" "Blue"
+ (binding color b #:default 1.0 #:group rgb-group)))
+ (fieldset
+ (legend "HSV")
+ ,(slider "hue" "Hue" 0 360 (binding color h #:group hsv-group))
+ ,(uslider "saturation" "Saturation" (binding color s #:group hsv-group))
+ ,(uslider "value" "Value" (binding color v #:group hsv-group))))))
generated by cgit v1.2.3 (git 2.25.4) at 2024-11-18 07:12:04 +0000