This is the second post related to I/O in F#
Directory
The Directory class offers similar functionality to the File class. It has Create and Delete methods, as well as helpers to enumerate the directories.
open System.IO
let path = Path.Combine(".", "my-dir")
let dirinfo = Directory.CreateDirectory(path)
printfn $"%s{dirinfo.Name} - %s{dirinfo.FullName}"
// my-dir - C:\Users\scyth\repos\blogpostdrafts\my-dir
// To Delete the directory
// use either dirinfo.Delete
// dirinfo.Delete()
// or Directory.Delete
Directory.Delete(dirinfo.FullName)
If you try to delete a directory that is not empty, you will get an exception. You can just pass a Boolean to recursively delete everything within that directory.
Directory.Delete(dirinfo.FullName, true)
// or
dirinfo.Delete(true)
That is pretty nice, and if you pay attention to the IDE hints, you'll see that CreateDirectory returns a DirectoryInfo instance which is another class that also has more less the same methods that Directory has. The motivation is that DirectoryInfo operates on a specific directory, instead of a general-purpose class for directories.
What if we want to get the files and directories on the current path?
open System.IO
let files =
Directory.EnumerateFiles(".")
|> Seq.fold (fun prev next -> $"{prev}\n\t{next}") ""
let directories =
Directory.EnumerateDirectories(".")
|> Seq.fold (fun prev next -> $"{prev}\n\t{next}") ""
printfn $"files:\t{files}\n directories:\t{directories}"
The output would be something like:
files:
.\README.md
.\sample.log
.\simple-things-in-fsharp-1.md
directories:
.\.git
.\.ionide
.\samples
.\scriptsYou can create a DirectoryInfo instance yourself:
open System.IO
let dir = DirectoryInfo(".")
let dirs = dir.EnumerateDirectories()
let files = dir.EnumerateFiles()
printfn "directories: %s\nfiles: %s" (dirs.GetType().ToString()) (files.GetType().ToString())
// directories: System.IO.Enumeration.FileSystemEnumerable`1[System.IO.DirectoryInfo]
// files: System.IO.Enumeration.FileSystemEnumerable`1[System.IO.FileInfo]If you want to recursively travel through all the sub-directories within a directory, you can use SearchOption.AllDirectories which will get us a flat list of directories in the specified path.
open System.IO
let dir = DirectoryInfo(".")
let directories = dir.GetDirectories("*.*", SearchOption.AllDirectories)
printfn "%A" directories
(*
[|C:\Users\scyth\repos\blogpostdrafts\.git;
C:\Users\scyth\repos\blogpostdrafts\.ionide;
C:\Users\scyth\repos\blogpostdrafts\samples;
C:\Users\scyth\repos\blogpostdrafts\scripts;
C:\Users\scyth\repos\blogpostdrafts\.git\hooks;
C:\Users\scyth\repos\blogpostdrafts\.git\info;
C:\Users\scyth\repos\blogpostdrafts\.git\logs;
C:\Users\scyth\repos\blogpostdrafts\.git\objects;
C:\Users\scyth\repos\blogpostdrafts\.git\refs;
C:\Users\scyth\repos\blogpostdrafts\samples\samples2;
C:\Users\scyth\repos\blogpostdrafts\.git\logs\refs;
C:\Users\scyth\repos\blogpostdrafts\.git\objects\info;
C:\Users\scyth\repos\blogpostdrafts\.git\objects\pack;
C:\Users\scyth\repos\blogpostdrafts\.git\refs\heads;
C:\Users\scyth\repos\blogpostdrafts\.git\refs\remotes;
C:\Users\scyth\repos\blogpostdrafts\.git\refs\tags;
C:\Users\scyth\repos\blogpostdrafts\samples\samples2\samples3;
C:\Users\scyth\repos\blogpostdrafts\.git\logs\refs\heads;
C:\Users\scyth\repos\blogpostdrafts\.git\logs\refs\remotes;
C:\Users\scyth\repos\blogpostdrafts\.git\refs\remotes\origin;
C:\Users\scyth\repos\blogpostdrafts\samples\samples2\samples3\samples4;
C:\Users\scyth\repos\blogpostdrafts\.git\logs\refs\remotes\origin|]
*)This is the output in this specific case. You can play with the pattern to filter out unwanted directories.
Let's now do a relatively common exercise and create a tree like structure of the directory layout.
NOTE: Please keep in mind that this might not be the best way to implement this and is not the best solution. It's just one way to implement.
open System.IO
// first let's define our data type that will
type Hierarchy =
{ Name: string
Files: string list
Directories: Hierarchy list }
let getFiles (dir: DirectoryInfo) =
dir.EnumerateFiles()
|> Seq.map (fun file -> file.FullName)
|> List.ofSeq
let getDirectories (dir: DirectoryInfo) =
dir.EnumerateDirectories()
|> Seq.filter (fun dir -> not (dir.Name.StartsWith(".")))
|> List.ofSeq
/// we'll define a recursive function that will take a `List<DirectoryInfo>`
/// and returns a `List<Hierarchy>`
let rec getDirHierarchy (directories: DirectoryInfo list) =
directories
|> List.map
(fun dir ->
{ Name = dir.FullName
Files = getFiles dir
Directories = getDirHierarchy (getDirectories dir) })
let getHierarchy (path: string) =
let dir = DirectoryInfo(path)
{ Name = dir.FullName
Files = getFiles dir
Directories = getDirHierarchy (getDirectories dir) }
let hierarchy = getHierarchy "."
printfn $"%A{hierarchy}"
(*
{ Name = "C:\Users\scyth\repos\blogpostdrafts"
Files =
[C:\Users\scyth\repos\blogpostdrafts\README.md;
C:\Users\scyth\repos\blogpostdrafts\sample.log;
C:\Users\scyth\repos\blogpostdrafts\simple-things-in-fsharp-1.md;
C:\Users\scyth\repos\blogpostdrafts\simple-things-in-fsharp-2.md]
Directories =
[{ Name = "C:\Users\scyth\repos\blogpostdrafts\samples"
Files = [C:\Users\scyth\repos\blogpostdrafts\samples\moved.txt]
Directories =
[{ Name = "C:\Users\scyth\repos\blogpostdrafts\samples\samples2"
Files =
[C:\Users\scyth\repos\blogpostdrafts\samples\samples2\moved2.txt]
Directories =
[{ Name =
"C:\Users\scyth\repos\blogpostdrafts\samples\samples2\samples3"
Files = []
Directories =
[{ Name =
"C:\Users\scyth\repos\blogpostdrafts\samples\samples2\samples3\samples4"
Files = []
Directories = [] }] }] }] };
{ Name = "C:\Users\scyth\repos\blogpostdrafts\scripts"
Files =
[C:\Users\scyth\repos\blogpostdrafts\scripts\http.fsx;
C:\Users\scyth\repos\blogpostdrafts\scripts\stif-1-2.fsx;
C:\Users\scyth\repos\blogpostdrafts\scripts\stif-1-3.fsx;
C:\Users\scyth\repos\blogpostdrafts\scripts\stif-1-4.fsx;
C:\Users\scyth\repos\blogpostdrafts\scripts\stif-1-5.fsx;
C:\Users\scyth\repos\blogpostdrafts\scripts\stif-1-6.fsx;
C:\Users\scyth\repos\blogpostdrafts\scripts\stif-1-7.fsx;
C:\Users\scyth\repos\blogpostdrafts\scripts\stif-1-8.fsx;
C:\Users\scyth\repos\blogpostdrafts\scripts\stif-1.fsx]
Directories = [] }] }
*)To move a directory and all of its contents, simply use the DirectoryInfo.MoveTo or Directory.Move but please keep in mind that MoveTo is a method of DirectoryInfo instance
open System.IO
Directory.Move("./samples", "./samples2")
// check the directory was moved before running the last bits
let dir = DirectoryInfo("./samples2")
// move it back to it's original place
dir.MoveTo("./samples")About Encora
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