neva-to-mermaid

Documents

Convert Neva programs to valid Mermaid flowchart diagrams. Use when asked to visualize Neva code as Mermaid.

QUICK START

How to use this skill

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Open your project in Codex.
Copy the prompt below and paste it into your agent.
Review the proposed files and risks before you approve installation.

Prompt to paste

I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/nevalang/neva/blob/HEAD/.codex/skills/neva-to-mermaid/SKILL.md

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First, summarize what it does, its dependencies, license status if identifiable, and any risks. Show the exact files you propose to add under .agents/skills/neva-to-mermaid/. Do not write files or run scripts until I approve.

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Copying this prompt does not install or run the skill. Review third-party files before use. Codex skill guide

Neva to Mermaid

Use this skill to convert any Neva source code into a Mermaid flowchart.

Instructions

Read the Neva code to be converted.
Generate a Mermaid flowchart TB diagram using the following rules:
- Layout: Always include this header at the top:
```
---
config:
  layout: elk
---
flowchart TB
```
- Ports:
  - Use stadium shapes for external ports :in / :out:
    - ([":data"]), ([":res"]), ([":err"]), etc.
  - In edges, label with the port name (data, res, err, sig, case[0], etc).
- Components:
  - Use unique Mermaid node IDs.
  - Render component nodes as regular boxes using only their declared instance name: id["name"].
  - Do not annotate component nodes with type names, generic parameters, or usage information.
- Literals:
  - Render numeric and string literals as rectangles using Mermaid shape syntax:
    - zero@{ label: "0", shape: rect }
    - dot@{ label: "'.'", shape: rect }
- Connections:
  - Use -- <port> --> labels for the wire’s port name.
  - For a:out -> b:in, label the edge with the output port name (out), unless Neva explicitly uses the input port name in the wiring (e.g., b:sig).
  - Only label an edge with a port name when the Neva source explicitly names a port on that connection.
    - Examples that MUST be labeled:
    - x:res -> y → label edge as res
    - x -> y:sig → label edge as sig
    - x:case[0] -> y → label edge as case[0]
- If a port name is omitted in Neva, do not infer or guess it. Render an unlabeled edge:
  - x -> y → x --> y
- Fan-out / Fan-in (IMPORTANT):
  - Mermaid edges do not create real “ports as objects”, so list-wiring must be represented explicitly with virtual junction nodes.
  - A junction node is a small circle: jX(( )) where jX is a unique ID.
  Fan-out: src -> [a, b, :out]
  - Insert a junction node jX(( )).
  - Wire: src -- <port> --> jX
  - Then wire: jX --> a, jX --> b, jX --> out_port
  Fan-in: [a, b] -> dst:port
  - Insert a junction node jX(( )).
  - Wire: a --> jX and b --> jX
  - Then wire: jX -- <port> --> dst
- Grouping (&):
  - You MAY use & to reduce clutter only when it does not hide fan-in/fan-out topology.
  - If Neva uses list-wiring ([...]), prefer junction nodes over &.
Do not look up other files in the repo or call web search; this text describes the conversion rules.
Ensure the output is ready to be pasted into the Mermaid playground.

Reference Example

Neva

pub def Tap<T>(data T) (res T, err error) {
    pass1 Pass<T>
    pass2 Pass<T>
    lock Lock<T>
    handler ITapHandler<T>
    ---
    :data -> [lock:data, handler]
    handler:res -> pass1
    handler:err -> [pass2, :err]
    [pass1, pass2] -> lock:sig
    lock -> :res
}