Nimic is a pure Python module that facilitates writing AOT compilable code with a subset of Python (domain specific language), aiming to get C-level performance without leaving Python. Based on ctypes built-in module, it includes emulation of native types, pointers and operations on them, implementing dispatch, operator overloading, and templates. Nimic closely follows Nim programming language, to which nimic code transpiles.

Key principle: nimic code is valid Python that runs natively and transpiles to equivalent Nim code.

Module Architecture

nimic/
├── ntypes.py       — Public API: re-exports type system + Nim keyword/builtin shims
├── ntypesystem.py  — Core type system (Object, NScalar, seq, dispatch, distinct, converter)
├── transpiler.py   — AST-based Python → Nim source code transpiler
├── inliner.py      — Template function inlining (@template, @template_expand)
├── ncode/          — Nim definitions (pydefs.nim, pystd/)
├── nimpy/          — API for generating Python libraries
├── std/            — Python shims for Nim stdlib (math, options, os, paths, strformat, ...)
└── system/         — Python shims for Nim system modules (ansi_c)

ntypesystem.py — Core Type System

Organized in layers from low-level memory to high-level abstractions:

ntypes.py — Public API & Keywords

Re-exports all of ntypesystem and adds Nim keyword/builtin emulation:

• Compiler hints — const, let, var, block, export, alias (no-ops in Python, scoping in Nim)
• Reference types — ref, ptr, mut@ (@ operator returns identity)
• Enum utilities — NStrEnum with succ/pred/ord/nrange/low/high
• Cast & memory — cast[T](x), sizeof(x), addr(x), unsafe_addr(x)
• Type aliases — SomeInteger, SomeFloat, untyped, char, u64, i64, f64
• Iteration — fields(obj), fields(a, b), countdown(a, b)
• Compile-time — comptime(x), defined(varname), static
• Templates — @template, @template_expand (re-exported from inliner)

transpiler.py — Python → Nim Transpiler

A modified CPython ast.py where _Unparser is extended to emit Nim syntax. Implements 30+ transformation rules for indentation, type definitions, function signatures, operators, imports, and control flow.

inliner.py — Template Inlining

@template + @template_expand decorators perform AST-level function inlining for untyped templates, substituting parameter names with call arguments.

DSL Conventions

Nimic uses Python syntax with specific conventions that have dual meaning — runtime behavior in Python and transpilation semantics for Nim:

Projects built with nimic

• Raytracer, including a ppm to mp4 converter
• Python module for preprocessing image data

Quick Example

from __future__ import annotations
from nimic.ntypes import *

# Struct definition (Nim object)
class Vec3(Object):
    x: float64
    y: float64
    z: float64

    def __add__(self: Vec3, v: Vec3) -> Vec3:
        """{.inline.}"""
        result = Vec3()
        result.x = self.x + v.x
        result.y = self.y + v.y
        result.z = self.z + v.z
        return result

# Distinct type
@distinct
class Point3(Vec3):
    """{.borrow: `.`.}"""

# Multi-dispatch
@dispatch
def point3(x: float64, y: float64, z: float64) -> Point3:
    result = Point3(Vec3())
    result.x = x; result.y = y; result.z = z
    return result

# Usage
with let:
    a = point3(1.0, 2.0, 3.0)
    b = point3(4.0, 5.0, 6.0)
    c = Vec3(a) + Vec3(b)