feat: add LangChainGo Huggingface backend (#446)

Co-authored-by: Ettore Di Giacinto <mudler@users.noreply.github.com>

pkg/langchain/huggingface.go

@@ -0,0 +1,47 @@
+package langchain
+
+import (
+	"context"
+
+	"github.com/tmc/langchaingo/llms"
+	"github.com/tmc/langchaingo/llms/huggingface"
+)
+
+type HuggingFace struct {
+	modelPath string
+}
+
+func NewHuggingFace(repoId string) (*HuggingFace, error) {
+	return &HuggingFace{
+		modelPath: repoId,
+	}, nil
+}
+
+func (s *HuggingFace) PredictHuggingFace(text string, opts ...PredictOption) (*Predict, error) {
+	po := NewPredictOptions(opts...)
+
+	// Init client
+	llm, err := huggingface.New()
+	if err != nil {
+		return nil, err
+	}
+
+	// Convert from LocalAI to LangChainGo format of options
+	co := []llms.CallOption{
+		llms.WithModel(po.Model),
+		llms.WithMaxTokens(po.MaxTokens),
+		llms.WithTemperature(po.Temperature),
+		llms.WithStopWords(po.StopWords),
+	}
+
+	// Call Inference API
+	ctx := context.Background()
+	completion, err := llm.Call(ctx, text, co...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Predict{
+		Completion: completion,
+	}, nil
+}