Nim for TypeScript Devs

#nim #javascript #typescript

Feature	TypeScript	Nim
Execution model	JavaScript code (Compiler)	JavaScript code (Compiler)
Written using	TypeScript	Nim
License	Apache	MIT
Version (Mayor)	`3.x`	`1.x`
Typing	Static	Static
Meta-programming	❎ #issue-13252, Decorators are limited	✔️ template, macro
int8/16/32/64 types	❎	✔️
float32/float64 types	❎	✔️
Char types	❎	✔️
Subrange types	❎ #issue-225324972	✔️
JSON types	❎ #issue-56296923	✔️
Regex types	❎ #issue-128264906	✔️
Option types	❎	✔️
Dependent types	❎	✔️
Operator Overloading	❎	✔️
Custom Operators	❎	✔️
Enum types	✔️	✔️
Immutability	Limited, `readonly` keyword	✔️
Function Arguments Immutability	Mutable	Immutable
Full DOM API	✔️	✔️
NodeJS integration	✔️	✔️
Generics	✔️	✔️
Type inference	✔️	✔️
Closures	✔️	✔️
Object-Oriented	✔️	✔️
Methods	✔️	✔️
Exceptions	✔️	✔️
Anonymous Functions	✔️	✔️
Arrow Functions	✔️	✔️
Array Comprehensions	✔️	✔️
Formatted String Literals	✔️	✔️
FFI	✔️ JS only	✔️ C/C++/JS
Async	✔️	✔️
Regex	✔️	✔️
Self-Documentation comments	✔️	✔️
Package Publishing	✔️	✔️
Package Manager	✔️	✔️
Code AutoFormatter	✔️ via NPM	✔️ Nimpretty
Syntax similar to	JavaScript	CoffeeScript or Python

Variables

Creating a new variable uses var or let or const.
Nim has immutability and compile-time function execution.
You can assign functions to variables.

const is different from TypeScript by being truly immutable.

Declaration	Compile-Time	Run-Time	Immutable	Requires Assignment
`var`	❎	✔️	❎	❎
`let`	❎	✔️	✔️	✔️
`const`	✔️	❎	✔️	✔️

Compile-Time Function Execution

Nim has Compile-Time Function Execution that allows you to run Backend-like code at compile-time and use it on Frontend at run-time.
Compile-time FFI is also possible, you can pull data from C/C++ libs at compile-time and use it on Frontend at run-time.
Most code that works at compile-time and NimScript also tends to work for Frontend.

Example: Compile-time recursive file system walk module.

Svelte

Nim has some similarities with Svelte for Frontend, but at the time of writing Svelte does not fully supports TypeScript.
Svelte can not do Backend (is not designed to).

Build Modes

Feature	Release Build	Debug Build
Speed	Fast	Slow
File Size	Small	Big
Optimized	✔️	❎
Tracebacks	❎	✔️
Run-time checks	❎	✔️
Compile-time checks	✔️	✔️
`assert`	❎	✔️
`doAssert`	✔️	✔️