Grain: Your WebAssembly-First Programming Language vs AssemblyScript

Grain: Your WebAssembly-First Programming Language - WebAssembly Summit 2021

Grain is strongly typed (with a typechecker from OCaml), and its type inference significantly reduces the need for type annotations. Besides the WebAssembly core data types (e.g., i32 becomes Int32), Grain also provides composite types that are commonly used in high-level typed languages.

AssemblyScript, which compiles a strict variant of TypeScript to WebAssembly, also self-describes as made for WebAssembly and includes a standard library with common composite types (e.g., arrays, dates). Like Grain, AssemblyScript compiles to WebAssembly using Binaryen. AssemblyScript strives to give 

developers low-level control within a higher-level language while remaining mindful of code size.

Oscar Spencer — Grain: Your WebAssembly-First Programming Language - YouTube

Grain: A strongly-typed functional programming language for the modern web.

WebAssembly Summit 2021