```typescript
import {
  ChatPromptTemplate,
  SystemMessagePromptTemplate,
  HumanMessagePromptTemplate
} from "langchain/prompts";

const template = "You are a helpful assistant that translates {input_language} to {output_language}.";
const systemMessagePrompt = SystemMessagePromptTemplate.fromTemplate(template);
const humanTemplate = "{text}";
const humanMessagePrompt = HumanMessagePromptTemplate.fromTemplate(humanTemplate);

const chatPrompt = ChatPromptTemplate.fromPromptMessages([systemMessagePrompt, humanMessagePrompt]);

const formattedPrompt = await chatPrompt.formatMessages({
  input_language: "English",
  output_language: "French",
  text: "I love programming."
});
```

```typescript
/*
  [
    SystemMessage {
      content: 'You are a helpful assistant that translates English to French.'
    },
    HumanMessage {
      content: 'I love programming.'
    }
  ]
*/
```