babel + typescript (#240)

* add tsconfig

* update package libs

* rename everything to *.ts

* add jest types

* tell eslint about typescript

* fix issue where eslint doesnt resolve ty pescript

* eslint lets you have unused _vars

* the fun part of typescript migration

* fix build

* have jest ask babel to transpile typescript before running tests

* no tsx files

* pin eslint typescript import resolver module

* remove support for node 15

* allow esmodules

.babelrc

@@ -1,3 +1,6 @@
 {
-  "presets": ["@babel/preset-env"]
+  "presets": [
+    ["@babel/preset-env", {"targets": {"node": "current"}}],
+    "@babel/preset-typescript"
+  ]
 }

.github/workflows/tests.yml

@@ -23,12 +23,13 @@ jobs:
       matrix:
         node-version:
           - 11.x # deprecated
-          - 12.x # maintainence ends 2022-04-30
+          - 12.x # deprecated
           - 13.x # deprecated
           - 14.x # maintainence ends 2023-04-30
           - 15.x # deprecated
           - 16.x # maintainence ends 2024-04-30
-          - 17.x # maintainence ends 2022-06-01
+          - 17.x # deprecated
+          - 18.x # maintainence ends 2025-04-30
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3

.npmignore

@@ -17,3 +17,4 @@ benchmark/*
 .husky/
 CONTRIBUTING.md
 .editorconfig
+tsconfig.json

package.json

@@ -3,7 +3,7 @@
   "version": "2.1.0",
   "description": "Weng-Lin Bayesian approximation method for online skill-ranking.",
   "scripts": {
-    "build": "babel src -d dist",
+    "build": "babel src --out-dir dist --extensions \".js,.ts\" --source-maps inline",
     "lint": "eslint src",
     "prepare": "husky install && npm run build",
     "release": "np",
@@ -31,9 +31,16 @@
     "@babel/cli": "7.18.6",
     "@babel/core": "7.18.6",
     "@babel/preset-env": "7.18.6",
+    "@babel/preset-typescript": "7.16.7",
     "@babel/register": "7.18.6",
     "@philihp/eslint-config": "5.1.2",
-    "husky": "8.0.1"
+    "@types/jest": "27.4.1",
+    "@typescript-eslint/eslint-plugin": "5.18.0",
+    "@typescript-eslint/parser": "5.18.0",
+    "eslint": "8.13.0",
+    "eslint-import-resolver-typescript": "2.7.1",
+    "husky": "7.0.4",
+    "typescript": "4.6.3"
   },
   "lint-staged": {
     "src/**/*.{js,jsx,json}": [
@@ -51,12 +58,60 @@
     ]
   },
   "eslintConfig": {
+    "parser": "@typescript-eslint/parser",
+    "parserOptions": {
+      "project": "./tsconfig.json"
+    },
+    "plugins": [
+      "@typescript-eslint"
+    ],
     "extends": [
       "@philihp",
-      "plugin:jest/all"
-    ]
+      "plugin:jest/all",
+      "plugin:@typescript-eslint/recommended"
+    ],
+    "settings": {
+      "import/extensions": [
+        ".js",
+        ".ts"
+      ],
+      "import/parsers": {
+        "@typescript-eslint/parser": [
+          ".ts"
+        ]
+      },
+      "import/resolver": {
+        "typescript": {},
+        "node": {
+          "extensions": [
+            ".js",
+            ".ts"
+          ]
+        }
+      }
+    },
+    "rules": {
+      "import/extensions": [
+        "error",
+        "ignorePackages",
+        {
+          "js": "never",
+          "ts": "never"
+        }
+      ],
+      "@typescript-eslint/no-unused-vars": [
+        "warn",
+        {
+          "argsIgnorePattern": "^_",
+          "varsIgnorePattern": "^_",
+          "caughtErrorsIgnorePattern": "^_"
+        }
+      ]
+    }
   },
   "dependencies": {
+    "@types/gaussian": "1.2.0",
+    "@types/ramda": "0.28.12",
     "gaussian": "1.2.0",
     "ramda": "0.28.0",
     "sort-unwind": "1.0.0"

src/constants.ts

@@ -0,0 +1,18 @@
+import { Options } from './types'
+
+export const z = (options: Options) => options?.z ?? 3
+export const mu = (options: Options) => options?.mu ?? 25
+export const sigma = (options: Options) =>
+  options?.sigma ?? mu(options) / z(options)
+
+export const epsilon = (options: Options) => options?.epsilon ?? 0.0001
+export const beta = (options: Options) => options?.beta ?? sigma(options) / 2
+export const betaSq = (options: Options) => beta(options) ** 2
+
+export default (options: Options) => ({
+  EPSILON: epsilon(options),
+  TWOBETASQ: 2 * betaSq(options),
+  BETA: beta(options),
+  BETASQ: betaSq(options),
+  Z: z(options),
+})

src/models/bradley-terry-full.js → src/models/bradley-terry-full.ts

@@ -1,7 +1,8 @@
 import util, { score } from '../util'
 import constants from '../constants'
+import { Rating, Options } from '../types'
 
-export default (game, options = {}) => {
+export default (game: Rating[][], options: Options = {}) => {
   const { TWOBETASQ, EPSILON } = constants(options)
   const { teamRating, gamma } = util(options)
   const teamRatings = teamRating(game)

src/models/bradley-terry-part.js → src/models/bradley-terry-part.ts

@@ -1,8 +1,9 @@
 import { zip } from 'ramda'
 import util, { score, ladderPairs } from '../util'
 import constants from '../constants'
+import { Rating } from '../types'
 
-export default (game, options = {}) => {
+export default (game: Rating[][], options = {}) => {
   const { TWOBETASQ, EPSILON } = constants(options)
   const { teamRating, gamma } = util(options)
 

src/models/plackett-luce.js → src/models/plackett-luce.ts

@@ -1,7 +1,8 @@
 import util, { utilSumQ, utilA } from '../util'
 import constants from '../constants'
+import { Rating, Options } from '../types'
 
-export default (game, options = {}) => {
+export default (game: Rating[][], options: Options = {}) => {
   const { EPSILON } = constants(options)
   const { utilC, teamRating, gamma } = util(options)
   const teamRatings = teamRating(game)

src/models/thurstone-mosteller-full.js → src/models/thurstone-mosteller-full.ts

@@ -1,8 +1,9 @@
 import util from '../util'
 import constants from '../constants'
 import { w, v, vt, wt } from '../statistics'
+import { Rating, Options } from '../types'
 
-export default (game, options = {}) => {
+export default (game: Rating[][], options: Options = {}) => {
   const { TWOBETASQ, EPSILON } = constants(options)
   const { teamRating, gamma } = util(options)
   const teamRatings = teamRating(game)

src/models/thurstone-mosteller-part.js → src/models/thurstone-mosteller-part.ts

@@ -2,8 +2,9 @@ import { zip } from 'ramda'
 import util, { ladderPairs } from '../util'
 import { w, v, vt, wt } from '../statistics'
 import constants from '../constants'
+import { Rating, Options } from '../types'
 
-export default (game, options = {}) => {
+export default (game: Rating[][], options: Options = {}) => {
   const { TWOBETASQ, EPSILON } = constants(options)
   const { teamRating, gamma } = util(options)
   const teamRatings = teamRating(game)

src/ordinal.ts

@@ -0,0 +1,10 @@
+import constants from './constants'
+import { Rating, Options } from './types'
+
+const ordinal = (rating: Rating, options: Options = {}) => {
+  const { sigma, mu } = rating
+  const { Z } = constants(options)
+  return mu - Z * sigma
+}
+
+export default ordinal

src/predict-draw.js → src/predict-draw.ts

@@ -2,8 +2,9 @@ import { flatten } from 'ramda'
 import constants from './constants'
 import util, { sum } from './util'
 import { phiMajor, phiMajorInverse } from './statistics'
+import { Rating, Options } from './types'
 
-const predictWin = (teams, options = {}) => {
+const predictWin = (teams: Rating[][], options: Options = {}) => {
   const { teamRating } = util(options)
   const { BETASQ, BETA } = constants(options)
 

src/predict-win.js → src/predict-win.ts

@@ -1,8 +1,9 @@
 import constants from './constants'
 import util, { sum } from './util'
 import { phiMajor } from './statistics'
+import { Rating, Options } from './types'
 
-const predictWin = (teams, options = {}) => {
+const predictWin = (teams: Rating[][], options: Options = {}) => {
   const { teamRating } = util(options)
   const { BETASQ } = constants(options)
 

src/rate.js → src/rate.ts

@@ -1,8 +1,9 @@
 import { sortBy, identity, range } from 'ramda'
 import unwind from 'sort-unwind'
 import models from './models'
+import { Rating, Options } from './types'
 
-const rate = (teams, options = {}) => {
+const rate = (teams: Rating[][], options: Options = {}) => {
   const model = models[options.model || 'plackettLuce']
   let processedTeams = teams
 
@@ -34,7 +35,7 @@ const rate = (teams, options = {}) => {
   // preventSigmaIncrease prevents sigma from ever going up which can happen when using a tau value.
   // this helps prevent ordinal from ever dropping after winning a game which can feel unfair
   if (options.tau && options.preventSigmaIncrease) {
-    reorderedTeams = reorderedTeams.map((team, i) =>
+    reorderedTeams = reorderedTeams.map((team: Rating[], i: number) =>
       team.map((p, j) => ({
         ...p,
         sigma: Math.min(p.sigma, teams[i][j].sigma),

src/rating.ts

@@ -0,0 +1,9 @@
+import { mu as defaultMu, sigma as defaultSigma } from './constants'
+import { Rating } from './types'
+
+const rating = (init?: Rating, options = {}) => ({
+  mu: init?.mu ?? defaultMu(options),
+  sigma: init?.sigma ?? defaultSigma({ ...options, mu: init?.mu }),
+})
+
+export default rating

src/statistics.js → src/statistics.ts

@@ -3,19 +3,19 @@ import gaussian from 'gaussian'
 // use a standard normal distribution - mean of zero, stddev/variance of one
 const normal = gaussian(0, 1)
 
-export const phiMajor = (x) => normal.cdf(x)
+export const phiMajor = (x: number) => normal.cdf(x)
 
-export const phiMajorInverse = (x) => normal.ppf(x)
+export const phiMajorInverse = (x: number) => normal.ppf(x)
 
-export const phiMinor = (x) => normal.pdf(x)
+export const phiMinor = (x: number) => normal.pdf(x)
 
-export const v = (x, t) => {
+export const v = (x: number, t: number) => {
   const xt = x - t
   const denom = phiMajor(xt)
   return denom < Number.EPSILON ? -xt : phiMinor(xt) / denom
 }
 
-export const w = (x, t) => {
+export const w = (x: number, t: number) => {
   const xt = x - t
   const denom = phiMajor(xt)
   if (denom < Number.EPSILON) {
@@ -24,7 +24,7 @@ export const w = (x, t) => {
   return v(x, t) * (v(x, t) + xt)
 }
 
-export const vt = (x, t) => {
+export const vt = (x: number, t: number) => {
   const xx = Math.abs(x)
   const b = phiMajor(t - xx) - phiMajor(-t - xx)
   if (b < 1e-5) {
@@ -35,7 +35,7 @@ export const vt = (x, t) => {
   return (x < 0 ? -a : a) / b
 }
 
-export const wt = (x, t) => {
+export const wt = (x: number, t: number) => {
   const xx = Math.abs(x)
   const b = phiMajor(t - xx) - phiMajor(-t - xx)
   return b < Number.EPSILON

src/types.ts

@@ -0,0 +1,25 @@
+export type Rating = {
+  mu: number
+  sigma: number
+}
+
+export type Model =
+  | 'thurstoneMostellerPart'
+  | 'thurstoneMostellerFull'
+  | 'bradleyTerryPart'
+  | 'bradleyTerryFull'
+  | 'plackettLuce'
+
+export type Options = {
+  z?: number
+  mu?: number
+  sigma?: number
+  epsilon?: number
+  gamma?: number
+  beta?: number
+  model?: Model
+  rank?: number[]
+  score?: number[]
+  tau?: number
+  preventSigmaIncrease?: boolean
+}