[R-sig-Geo] df with embedded wkt lists to sf

[Howard, Tim G (DEC)]

Howdy all - 
There's probably a way to do this much​ more simply than I've figured it out, so it's a bit embarrassing but here goes. I'm getting data out of a shiny app that looks like the following, with lists of coordinates within separate longitude and latitude columns. 

Is there more efficient way to get an `sf` collection than what I've got? Perhaps an `apply` replacement for the for() loop? Using a tibble because that's how `googlesheets4` gives it to me. 

# set up a couple of lines strings. lists within data.frame/tibble
txtString <- 'structure(list(comment = c("line one", "line two"), 
longitude = list("-115.138577; -114.942454; -114.170219", "-118.411382; -118.153971; -117.83527; -117.246901; -117.026262; -117.185613"), 
latitude = list("37.527588; 38.234088; 38.368805", "41.296472; 41.645606; 41.819467; 41.837741; 41.590604; 41.333312")), 
row.names = c(NA, -2L), class = c("tbl_df", "tbl", "data.frame"))'

dat <- dget(textConnection(txtString))

# function for parsing the text strings
getWKT <- function(x){
  st_linestring(matrix(
    c(as.numeric(unlist(strsplit(x$longitude[[1]],";"))),
      as.numeric(unlist(strsplit(x$latitude[[1]],";")))),
    byrow = FALSE, ncol = 2)
  )
}

# populate dataframe/tibble by going back to sf text
dat$wkt <- NA
for(i in 1:nrow(dat)){
  dat$wkt[[i]] <- st_as_text(getWKT(dat[i,]))
}

# finally make the sf collection
dat_sf <- st_as_sf(dat, wkt = "wkt", crs = 4326)


Thanks in advance for any tips. 
Tim