Execute Code with a Scoped LM Override

Temporarily sets a default LLM for all dsprrr operations within a code block. Similar to DSPy's dspy.context(lm=lm) context manager. When the block exits (normally or due to an error), the previous LM is restored.

Usage

with_lm(lm, code)

Arguments

lm

An ellmer Chat object to use as the default LLM within the block.

code

An expression to evaluate with the scoped LLM.

Value

The result of evaluating code.

Details

The scoped LM has higher priority than options(dsprrr.default_chat) and auto-detection, but lower priority than an explicit .llm parameter.

Resolution order (highest to lowest):

1. Explicit .llm parameter

2. Scoped LM from with_lm() / local_lm()

3. Module's stored $chat

4. options(dsprrr.default_chat)

5. Auto-detection from environment variables

Examples

if (FALSE) { # \dontrun{
# Use Claude for a specific block
claude <- ellmer::chat_claude()
result <- with_lm(claude, {
  dsp("question -> answer", question = "What is 2+2?")
  dsp("text -> summary", text = "Long article...")
})

# Nested contexts work correctly
gpt4 <- ellmer::chat_openai(model = "gpt-4o")
with_lm(gpt4, {
  run(mod1, text = "outer uses gpt4")
  with_lm(claude, {
    run(mod2, text = "inner uses claude")
  })
  run(mod3, text = "back to gpt4")
})
} # }