F# how to abstract Console.ReadLine() as string seq
Question
I want to write a function to abstract Console.ReadLine() into a string seq
the seq should break when line = null
ConsoleLines(): unit -> string seq
To be used like this:
for line in ConsoleLines() do
DoSomething line
How do you write this function?
Thanks
Solution
Seq.initInfinite (fun _ -> Console.ReadLine())
OTHER TIPS
Its not overly pretty, but it works as expected:
let rec ConsoleLines() =
seq {
match Console.ReadLine() with
| "" -> yield! Seq.empty
| x -> yield x; yield! ConsoleLines()
}
let ConsoleLines =
seq {
let finished = ref false
while not !finished do
let s = System.Console.ReadLine()
if s <> null then
yield s
else
finished := true
}
(Note that you must use ref/!/:= to do mutable state inside a sequence expression.)
let consoleLines = Seq.takeWhile ((<>) "") (seq { while (true) do yield System.Console.ReadLine() })
Slightly different:
let readLines (sr:TextReader) =
Seq.initInfinite (fun _ -> sr.ReadLine())
|> Seq.takeWhile (fun x -> x <> null)
let consoleLines() =
readLines Console.In
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