Port of https://github.com/tscircuit/stepts to MoonBit

cad

step

modeling

Download zip

Author

gmlewis

Version

0.1.3

License

Apache-2.0

Repository

github.com/gmlewis/moonbit-step

Last updated

9 months ago

Downloads

116

#gmlewis/step (MoonBit)

A high-level 3D modeling DSL and lossless STEP (ISO 10303-21) parser/serializer in MoonBit.

This repo allows you to build 3D models using a simple API and export them to valid, topologically-sound STEP files.

Onshape design: https://cad.onshape.com/documents/b8320fedf1f1ea6028755ae8/w/50dfab2e1185c97711b860a6/e/20263eabe6f1f22cc85a5a09?renderMode=0&uiState=695414a99e93423471a30e60

Example 12: The Bifilar Electromagnet, an invention of mine with interesting electrical properties.

#Quick Start (Modeling)

Building a model is intuitive:

async fn main {
  let design = @cad.Design::new(name="my-model")
    .add(
      @cad.Cuboid::new(20, 20, 20)
        .with_name("base")
        .with_color(@cad.Rgb::orange())
    )
    .add(
      @cad.CalibrationChamferBlock::new(10, 10, 5, chamfer_size_mm=1.0)
        .with_name("top-part")
        .translate(z=20)
    )

  design.write_step(Some("model.step"))
}

#Quick Start (Parsing)

Parsing from a string:

fn parse_example(step_text : String) -> Unit {
  match @parse.parse_repository_from_string_result(step_text) {
    @parse.ParseRepositoryResult::Ok(repo) => {
      let normalized = repo.to_step_file()
      println("entities=" + repo.len().to_string())
      println(normalized)
    }
    @parse.ParseRepositoryResult::Err(info) =>
      @cli.eprintln(@parse.format_step_parse_error(info))
  }
}

#Features

Fluent 3D DSL: Chain transformations like .translate(), .with_color(), and .with_name().
Lossless Roundtrips: Unknown/unmodeled entities are preserved during parse/serialize cycles.
Robust CLI: Built-in validation, proper stderr reporting, and short-circuiting exit codes.
Deterministic: Serializer output is stable (parse → serialize → parse is idempotent).

#Development & Validation

#Verification

Run the unit tests and formatters:

./test-all.sh

#Geometric Validation & Rendering

We use Open CASCADE (occt-draw or DRAWEXE) to ensure topological validity and generate previews:

./scripts/manage_examples.py all --validate --render --readme

#Goals

Provide a pleasant authoring UX for 3D models in MoonBit.
Parse real-world STEP files without panicking.
Provide actionable parse errors (line/col + statement snippets).

#License

Apache-2.0

#Status

The code has been updated to support compiler:

$ moon version --all
moon 0.1.20260110 (0e584ac 2026-01-10) ~/.moon/bin/moon
moonc v0.7.1+adb125543 (2026-01-10) ~/.moon/bin/moonc
moonrun 0.1.20260110 (0e584ac 2026-01-10) ~/.moon/bin/moonrun
moon-pilot 0.0.1-df92511 (2026-01-10) ~/.moon/bin/moon-pilot

Entity

source

pub(open) trait Entity {
  to_step(Self) -> String
}

EntityId

source

pub(all) struct EntityId {
  value : Int
}

RawEntity

source

pub struct RawEntity {
  name : String
  args : String
}

impl Entity for RawEntity

RawEntity::new

source

fn RawEntity::new(name : String, args : String) -> RawEntity

Ref

source

pub(all) struct Ref {
  id : EntityId
}

UnknownEntity

source

pub struct UnknownEntity {
}

fmt_num

source

fn fmt_num(n : Double) -> String

step_str

source

fn step_str(s : String) -> String

unknown_entity_witness

source

let unknown_entity_witness : UnknownEntity

Source Files

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step

#gmlewis/step (MoonBit)

#Quick Start (Modeling)

#Quick Start (Parsing)

#Features

#Development & Validation

#Verification

#Geometric Validation & Rendering

#Goals

#License

#Status

#Entity

#EntityId

#RawEntity

#RawEntity::new

#Ref

#UnknownEntity

#fmt_num

#step_str

#unknown_entity_witness

Source Files

Entity

EntityId

RawEntity

RawEntity::new

Ref

UnknownEntity

fmt_num

step_str

unknown_entity_witness