Functional TypeScript

package.json

{
...
  "scripts": {
    "lint": "ng lint --type-check",
...
  },
  "pre-commit": [
    "lint"
  ],
...

tslint.json

{
  "extends": ["tslint-immutable"],
  "rulesDirectory": [
    "../../../node_modules/codelyzer"
  ],
  "rules": {
    /* New rules to enable immutable checks */
    "typedef": [true, 
      "call-signature",
      "arrow-call-signature",
      "parameter",
      "arrow-parameter",
      "property-declaration",
      "variable-declaration",
      "member-variable-declaration",
      "object-destructuring",
      "array-destructuring"
    ],
    "readonly-keyword": false,
    "readonly-array": [true, "ignore-local"],
    "no-let": true,
    "no-any": true,
    /* existing rules follow */
...