← Library SliceDeterministic

SliceJoinOp

Joins a string slice into a single string using a separator.

Inputs

FieldTypeDescription
Input*[]stringSlice to join

Outputs

FieldTypeDescription
ResultstringElements joined by sep

Params

KeyTypeDefaultDescription
sepstring','Separator string

Typical Use Cases

  • Converting a label list to CSV for display
  • Building comma-separated prompt content
  • Joining extraction results into a single string

Complete Runnable Example

Joins a list of extracted keywords into a comma-separated string for inclusion in a prompt context.

main.go
package main

import (
	"context"
	"encoding/json"
	"log"
	"os"
	"time"

	"github.com/akennis/sparsi-go/library"
	_ "github.com/akennis/dagor/operator/builtin"

	"github.com/panjf2000/ants/v2"
	"github.com/akennis/dagor"
	"github.com/akennis/dagor/graph"
)

func main() {
	keywords := []string{"machine learning", "NLP", "transformers"}
	library.RegisterConst("keywords_val", keywords)

	g, err := graph.NewBuilder("slicejoin_demo").
		Vertex("src").Op("keywords_val").Output("Result", "wire_in").
		Vertex("jn").Op("SliceJoinOp").
		Params(map[string]string{"sep": ", "}).
		Input("Input", "wire_in").
		Output("Result", "joined").
		Build()
	if err != nil {
		log.Fatalf("build: %v", err)
	}

	pool, err := ants.NewPool(4)
	if err != nil {
		log.Fatalf("pool: %v", err)
	}
	defer pool.Release()

	eng, err := dagor.NewEngine(g, pool)
	if err != nil {
		log.Fatalf("engine: %v", err)
	}

	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
	defer cancel()

	if err := eng.Run(ctx); err != nil {
		log.Fatalf("run: %v", err)
	}

	out := map[string]any{"keywords": keywords}
	if raw, ok := eng.GetOutput("joined"); ok {
		out["joined"] = *raw.(*string)
	}
	enc := json.NewEncoder(os.Stdout)
	enc.SetIndent("", "  ")
	enc.Encode(out)
}