Reducer: keep only the last n entries

Appends new to old then trims the list to at most n entries by dropping the oldest. Use this instead of reducer_append() whenever the channel feeds into an LLM call, to prevent the context window from growing unboundedly and causing connection errors on long workflows.

Usage

reducer_last_n(n)

Arguments

n

Positive integer. Maximum number of entries to retain.

Value

A two-argument function function(old, new).

Examples

r <- reducer_last_n(3L)
r(list("a", "b", "c"), "d")   # drops "a", keeps "b", "c", "d"
#> [[1]]
#> [1] "b"
#> 
#> [[2]]
#> [1] "c"
#> 
#> [[3]]
#> [1] "d"
#>