Calls
- A call object represents a captured function call.
- Call objects are a special type of list.
- The first component specifies the function to call (usually a symbol).
- The remaining elements are the arguments for that call.
- Call objects create branches in the AST, because calls can be nested inside other calls.
- You can identify a call object when printed because it looks just like a function call.
- Confusingly
typeof() and str() print language for call objects, but is.call() returns TRUE:
lobstr::ast(read.table("important.csv", row.names = FALSE))
#> █─read.table
#> ├─"important.csv"
#> └─row.names = FALSE
x <- expr(read.table("important.csv", row.names = FALSE))
typeof(x)
#> [1] "language"