using 'input$entry' inside paste0 for variable length entry[1:n] - r

Question

I have a clunky block of shiny code on server.R side that I feel R syntax ought to allow me make one or two lines and simultaneously more flexible with some kind of lapply or do.call line
if(input$parVary == "area" && as.numeric(input$nTraces) > 3 )
{
area <- c(input$area, input$area2, input$area3, input$area4)
} else if(input$parVary == "area" && as.numeric(input$nTraces) > 2 )
{
area <- c(input$area, input$area2, input$area3)
} else if(input$parVary == "area" && as.numeric(input$nTraces) > 1 )
{
area <- c(input$area, input$area2)
} else
{
area <- input$area
}
But I have spent a day and about a billion different combos of lapply, do.calls, reactive, get, c, and observes around
paste0('input$area', 1:as.numeric(input$nTraces))
I just can't seem to find the right combination or figure out the reactive concept I'm missing. It -seems- to be related to the code not ever including individual input$area1, input$area2, etc... explicit text anywhere in the code?

Answer 1

I spoke a little too soon in comment above. My specific code ended up needing conditional to handle the list versus single value case. But #NicE answer is one I was looking for. Five sections like
if(input$parVary == "area" && as.numeric(input$nTraces) > 1 )
{
area <- lapply(paste0("area",1:as.numeric(input$nTraces)),function(x) input[[x]])
} else
{
area <- input$area1
}
teamed with later
mySolution <- list()
if(input$nTraces =='1')
{
mySolution <- solveCalc(dat=dat,tox=tox,area=area,temp=temp,model=modelIn)
} else
{
mySolution <- switch(input$parVary,
"model" = lapply(modelIn,solveCalc,dat=dat,tox=tox,area=area,temp=temp),
"temp" = lapply(temp,solveCalc,dat=dat,tox=tox,area=area,model=modelIn),
"tox" = lapply(tox,solveCalc,dat=dat,temp=temp,area=area,model=modelIn),
"Vt" = lapply(dat,solveCalc,tox=tox,temp=temp,area=area,model=modelIn),
"area" = lapply(area,solveCalc,dat=dat,tox=tox,temp=temp,model=modelIn)
)
}
Got me just what I wanted.