das-claude

March 9, 2026 · View on GitHub

Typed daslang bindings for the Anthropic Claude Messages API.

Install

daspkg install das-claude

Or from a local checkout:

daspkg install D:\DASPKG\das-claude

Quick start

options gen2

require anthropic/anthropic

[export]
def main() {
    var config <- claude_config_from_env()  // reads ANTHROPIC_API_KEY
    var error : string
    let reply = ask(config, "What is daslang?", error)
    if (!empty(error)) {
        print("error: {error}\n")
        return
    }
    print("{reply}\n")
}

Features

One-shot question

let reply = ask(config, "Hello!", error)

Full message control

var params : MessageCreateParams
params.system = "You are a helpful assistant."
params.messages |> emplace(user_message("What is 2+2?"))
var msg = create_message(config, params, error)
print("{get_text(msg)}\n")

Tool use

var params : MessageCreateParams
params.tools |> emplace(Tool(
    name = "get_weather",
    description = "Get weather for a city",
    input_schema = write_json(JV({
        "type" => JV("object"),
        "properties" => JV({ "city" => JV({ "type" => JV("string") }) }),
        "required" => JV(req_arr)
    }))
))
params.messages |> emplace(user_message("What's the weather in Paris?"))

var msg = run_tool_loop(config, params, $(tc : ToolUseBlock) : string {
    // handle tool call, return result as string
    return "{\"temperature\": 22, \"condition\": \"sunny\"}"
}, error)

API

Configuration

Function	Description
`claude_config(api_key)`	Create config with explicit API key
`claude_config_from_env()`	Create config from `ANTHROPIC_API_KEY` env var

Both accept optional named arguments: model, max_tokens, base_url.

HTTP client

Function	Description
`create_message(config, params, error)`	Send a Messages API request
`ask(config, prompt, error)`	One-shot text question
`run_tool_loop(config, params, handler, error)`	Multi-turn tool use loop

Request builders

Function	Description
`user_message(text)`	Single-text user message
`user_message(blocks)`	Multi-block user message
`assistant_message(text)`	Single-text assistant message
`text_param(text)`	Text content block
`tool_result_param(id, content)`	Tool result content block

Response helpers

Function	Description
`get_text(msg)`	Extract concatenated text from response
`get_tool_calls(msg)`	Extract tool use blocks
`has_tool_use(msg)`	Check if response contains tool calls

Serialization

Function	Description
`build_request_json(params)`	Serialize request to JSON string
`parse_response(json, error)`	Parse JSON response into `Message`
`parse_stream_event(json, error)`	Parse SSE event JSON into `StreamEvent`

Types

All types match the Claude Messages API schema:

Request: MessageCreateParams, MessageParam, ContentBlockParam (variant), Tool, ToolChoiceParam (variant)
Response: Message, ContentBlock (variant: text/tool_use/thinking), Usage
Streaming: StreamEvent (variant), ContentBlockDelta (variant)

Dependencies

Built-in daScript modules only — no external packages required:

daslib/json_boost — JSON serialization
dashv/dashv_boost — HTTP client
fio — environment variables

Tests

# Serialization tests (no API key needed)
daslang.exe dastest/dastest.das -- --test D:\DASPKG\das-claude\test_anthropic.das

# Integration tests (requires ANTHROPIC_API_KEY)
daslang.exe dastest/dastest.das -- --test D:\DASPKG\das-claude\test_client.das

License

MIT