Question

I was wondering what the preferred method is to convert lazy text into a list of strict texts split up by line endings. I came up with something like the following, but am not sure that I’m guaranteed that each strict text element will be a complete line (or if there are other problems with it):

import qualified Data.Text.Lazy as LT

readLines filePath = do
    contents <- Data.Text.Lazy.IO.readFile filePath
    let lines = concat (map LT.toChunks (LT.lines contents))
    return lines

Answer 1

readLines filePath = do
    contents <- Data.Text.Lazy.IO.readFile filePath
    let lines = concat (map LT.toChunks (LT.lines contents))
    return lines

doesn’t guarantee that each strict chunk is a complete line. In fact, every time a chunk boundary of the lazy Text does not coincide with a line boundary, you get a line having part in at least two strict chunks.

readLines filePath = do
    contents <- Data.Text.Lazy.IO.readFile filePath
    let lines = map (T.concat . LT.toChunks) (LT.lines contents)
    return lines

however, concatenates each line into one strict chunk. Doing the concatenation may however be slower than working with each line as a list of strict chunks resp. a lazy Text.