Nexus A LLM-friendly language
GitHub

Nexus is a programming language built on one premise: LLMs are strong at literal program constructs but weak at contextual ones. Garbage collection, implicit conversions, ambient I/O, continuation-based control flow — these contextual mechanisms are where LLM-generated code breaks and where human review fails. Nexus replaces them with syntactically explicit alternatives.

Coeffects – Hello world

Capability requirements declared in function signatures. Dependency injection via ports and handlers.

import { Console }, * as stdio from "stdlib/stdio.nx"



let main = fn () -> unit require { PermConsole } do

  inject stdio.system_handler do

    Console.println(val: "Hello, Nexus!")

  end

end

Linear Types

Resources consumed exactly once. No GC — the compiler tracks every allocation.

let %h = Fs.open_read(path: "data.txt")

let %r = Fs.read(handle: %h)

match %r do

  case { content: text, handle: %h2 } ->

        Fs.close(handle: %h2)

end

Conc Blocks

Parallel tasks with captured variables. Compiles to WASM with WASI capabilities.

let %arr = [| 0, 0 |]

conc do

  task t1 do

    let r = &%arr; r[0] <- compute_a()

  end

  task t2 do

    let r = &%arr; r[1] <- compute_b()

  end

end

Quick Start

nexus                   # REPL
nexus run example.nx    # interpret
nexus build example.nx  # compile to main.wasm
nexus check example.nx  # typecheck only

Design

Language Specification

Environment