yaml

yaml

Export an F-Mesh mesh as YAML: its structure, or its state in one cycle of a run. Use it for config-style review, diffs in pull requests, or snapshots in tests.

New() returns an Exporter. It implements this module's export.Exporter, like every format in this module. It has no options and no state: reuse one value for many meshes.

The documents are exactly the ones the json exporter writes, in YAML syntax. Both packages share the types: yaml.Mesh is json.Mesh.

Install

go get github.com/hovsep/fmesh-export/yaml

Structure

import "github.com/hovsep/fmesh-export/yaml"

data, err := yaml.New().Export(fm)

name: pricing
description: computes prices
meta:
  env: prod
components:
  - name: dst
    inputs:
      - name: in
        description: prices in
    outputs: []
  - name: src
    description: emits prices
    meta:
      weight: 2
    inputs:
      - name: start
    outputs:
      - name: out
pipes:
  - from:
      component: src
      port: out
    to:
      component: dst
      port: in

• Components and ports are in name order, metadata keys sorted. Pipes are grouped by source port, in the same order, and each port's pipes are in wiring order. The same mesh always exports the same bytes.
• description and meta are left out when empty. components, inputs, outputs and pipes are always present.
• Names are quoted when YAML needs it (a: b, #x, yes, null, ...), so they read back as written.
• Unmarshal into yaml.Mesh to read it back, for example with go.yaml.in/yaml/v3.
• A float metadata value with no fraction is written as an integer (2.0 → 2), so it reads back as an int into map[string]any.

One cycle

ri, err := fm.Run(ctx)
for _, c := range ri.Cycles.All() {
    frame, err := yaml.New().ExportCycle(fm, c)
}

The document is a yaml.Cycle: the cycle number, the mesh structure, and one results entry per component, in name order:

results:
  - component: dst
    code: Finished with error
    activated: true
    errors:
      - 'component returned an error: boom'
  - component: src
    code: No input
    activated: false

• A component with no result in the cycle had no input: its code is No input.
• A nil mesh returns export.ErrNilMesh, and a nil cycle export.ErrNilCycle.
• To export each cycle while the mesh runs, call ExportCycle from an AfterCycle hook.