Generate a random list

5 files changed, 106 insertions, 18 deletions

diff --git a/pbt/ts/package-lock.json b/pbt/ts/package-lock.json
index 4e4aeff..56e87d3 100644
--- a/pbt/ts/package-lock.json
+++ b/pbt/ts/package-lock.json
@@ -5,6 +5,8 @@
   "packages": {
     "": {
       "dependencies": {
+        "dotenv": "^16.4.7",
+        "prando": "^6.0.1",
         "typescript": "^5.7.3"
       },
       "devDependencies": {
@@ -809,6 +811,18 @@
         "node": ">=6.0.0"
       }
     },
+    "node_modules/dotenv": {
+      "version": "16.4.7",
+      "resolved": "https://registry.npmjs.org/dotenv/-/dotenv-16.4.7.tgz",
+      "integrity": "sha512-47qPchRCykZC03FhkYAhrvwU4xDBFIj1QPqaarj6mdM/hgUzfPHcpkHJOn3mJAufFeeAxAzeGsr5X0M4k6fLZQ==",
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "url": "https://dotenvx.com"
+      }
+    },
     "node_modules/emoji-regex": {
       "version": "8.0.0",
       "resolved": "https://registry.npmjs.org/emoji-regex/-/emoji-regex-8.0.0.tgz",
@@ -2324,6 +2338,12 @@
         "url": "https://github.com/sponsors/jonschlinkert"
       }
     },
+    "node_modules/prando": {
+      "version": "6.0.1",
+      "resolved": "https://registry.npmjs.org/prando/-/prando-6.0.1.tgz",
+      "integrity": "sha512-ghUWxQ1T9IJmPu6eshc3VU0OwveUtXQ33ZLXYUcz1Oc5ppKLDXKp0TBDj6b0epwhEctzcQSNGR2iHyvQSn4W5A==",
+      "license": "MIT"
+    },
     "node_modules/prelude-ls": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/prelude-ls/-/prelude-ls-1.2.1.tgz",
diff --git a/pbt/ts/package.json b/pbt/ts/package.json
index 5aab336..c11b4ba 100644
--- a/pbt/ts/package.json
+++ b/pbt/ts/package.json
@@ -1,11 +1,13 @@
 {
   "dependencies": {
+    "dotenv": "^16.4.7",
+    "prando": "^6.0.1",
     "typescript": "^5.7.3"
   },
   "devDependencies": {
+    "@types/node": "^22.7.5",
     "gts": "^6.0.2",
-    "typescript": "^5.6.3",
-    "@types/node": "^22.7.5"
+    "typescript": "^5.6.3"
   },
   "scripts": {
     "lint": "gts lint",
@@ -14,6 +16,7 @@
     "fix": "gts fix",
     "prepare": "npm run compile",
     "pretest": "npm run compile",
-    "posttest": "npm run lint"
+    "posttest": "npm run lint",
+    "app": "node build/src/index.js"
   }
 }
diff --git a/pbt/ts/src/index.ts b/pbt/ts/src/index.ts
index 3a71ccf..46454f0 100644
--- a/pbt/ts/src/index.ts
+++ b/pbt/ts/src/index.ts
@@ -1,20 +1,32 @@
-type Result = 'OK' | 'Falsified' | 'Exception';
+import "dotenv/config";
+import Prando from 'prando';
+import { Gen } from "./property";
 
-type TestResult<A> = {
-  result: Result,
-  seed: number,
-  counterexample: A | null
-};
+let genint: Gen<number> = (rng: Prando) =>
+  (size: number) =>
+  rng.nextInt(-size, size);
 
-type Predicate<A> = (a: A) => boolean;
 
-type Gen<A> = (s: number) => (() => A);
+function genlist<A>(gen: Gen<A>): Gen<A[]> {
+  return (rng: Prando) => {
+    let g = gen(rng);
+    return (size: number) => {
+      let result = [];
+      for (let i = 0; i < size; i++) {
+        result.push(g(size));
+      }
+      return result;
+    };
+  };
+}
 
-type Shrinker<A> = (a: A) => [A];
+function generate<A>(gen: Gen<A>): A {
+  let rng = new Prando(Math.random() * 1000);
+  return gen(rng)(100);
+}
 
-function property<A>(seed: number,
-  predicate: Predicate<A>,
-  generator: Gen<A>,
-  shrinker: Shrinker<A>): TestResult<A> {
-  return {result: 'OK', seed, counterexample: null};
+async function main() {
+  console.log('list: ' + generate(genlist(genint)));
 }
+
+main();
diff --git a/pbt/ts/src/property.ts b/pbt/ts/src/property.ts
new file mode 100644
index 0000000..e8d3a21
--- /dev/null
+++ b/pbt/ts/src/property.ts
@@ -0,0 +1,53 @@
+import Prando from "prando";
+
+type Result = 'OK' | 'Falsified' | 'Exception';
+
+type ShrinkResult<A> = { counterexample: A, shrinks: number };
+
+type TestResult<A> = {
+  result: Result,
+  counterexample: ShrinkResult<A> | null
+};
+
+type Predicate<A> = (a: A) => boolean;
+
+export type Gen<A> = (rng: Prando) => ((size: number) => A);
+
+type Shrinker<A> = (a: A) => [A];
+
+const MAX_SUCCESS = 100;
+
+function findMinimalCounterExample<A>(x: A,
+  predicate: Predicate<A>,
+  shrinker: Shrinker<A>,
+  depth: number = 0): ShrinkResult<A> {
+  let xs = shrinker(x);
+  let counterexample = x;
+  let shrinks = depth;
+  for (let y of xs) {
+    if (!predicate(y)) {
+      let shrink = findMinimalCounterExample(y, predicate, shrinker, depth + 1);
+      if (shrink.shrinks > depth) {
+        counterexample = shrink.counterexample;
+        shrinks = shrink.shrinks;
+      }
+    }
+  }
+  return { counterexample, shrinks };
+}
+
+export function property<A>(rng: Prando,
+  size: number,
+  predicate: Predicate<A>,
+  generator: Gen<A>,
+  shrinker: Shrinker<A>): TestResult<A> {
+  let gen = generator(rng);
+  for (let i = 0; i < MAX_SUCCESS; i++) {
+    let x = gen(size);
+    if (!predicate(x)) {
+      let counterexample = findMinimalCounterExample(x, predicate, shrinker);
+      return { result: 'Falsified', counterexample };
+    }
+  }
+  return { result: 'OK', counterexample: null };
+}
diff --git a/pbt/ts/tsconfig.json b/pbt/ts/tsconfig.json
index d1646f0..15fbe0f 100644
--- a/pbt/ts/tsconfig.json
+++ b/pbt/ts/tsconfig.json
@@ -7,5 +7,5 @@
   "include": [
     "src/**/*.ts",
     "test/**/*.ts"
-  ]
+, "src/property.ts~", "src/index.ts~"  ]
 }