Async hashing

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open System
open System.IO
open System.Security.Cryptography

// synchronous file hashing
let hashFile f = 
    use fs = new FileStream(f, FileMode.Open)
    use hashFunction = new SHA512Managed()
    hashFunction.ComputeHash fs |> Convert.ToBase64String

// async stream hashing
let hashAsync bufferSize (hashFunction: HashAlgorithm) (stream: Stream) =
    let rec hashBlock currentBlock count = async {
        let buffer = Array.zeroCreate<byte> bufferSize
        let! readCount = stream.AsyncRead buffer
        if readCount = 0 then
            hashFunction.TransformFinalBlock(currentBlock, 0, count) |> ignore
        else 
            hashFunction.TransformBlock(currentBlock, 0, count, currentBlock, 0) |> ignore
            return! hashBlock buffer readCount
    }
    async {
        let buffer = Array.zeroCreate<byte> bufferSize
        let! readCount = stream.AsyncRead buffer
        do! hashBlock buffer readCount
        return hashFunction.Hash |> Convert.ToBase64String
    }

// async file hashing
let hashFileAsync f =    
    let bufferSize = 32768
    async {
        use fs = File.OpenRead f
        use hashFunction = new SHA512Managed()
        return! hashAsync bufferSize hashFunction fs
    }

namespace System

namespace System.IO

namespace System.Security

namespace System.Security.Cryptography

val hashFile : f:string -> string

Full name: Script.hashFile

val f : string

val fs : FileStream

Multiple items
type FileStream =
  inherit Stream
  new : path:string * mode:FileMode -> FileStream + 14 overloads
  member BeginRead : array:byte[] * offset:int * numBytes:int * userCallback:AsyncCallback * stateObject:obj -> IAsyncResult
  member BeginWrite : array:byte[] * offset:int * numBytes:int * userCallback:AsyncCallback * stateObject:obj -> IAsyncResult
  member CanRead : bool
  member CanSeek : bool
  member CanWrite : bool
  member EndRead : asyncResult:IAsyncResult -> int
  member EndWrite : asyncResult:IAsyncResult -> unit
  member Flush : unit -> unit + 1 overload
  member GetAccessControl : unit -> FileSecurity
  ...

Full name: System.IO.FileStream

--------------------
FileStream(path: string, mode: FileMode) : unit
   (+0 other overloads)
FileStream(handle: Win32.SafeHandles.SafeFileHandle, access: FileAccess) : unit
   (+0 other overloads)
FileStream(path: string, mode: FileMode, access: FileAccess) : unit
   (+0 other overloads)
FileStream(handle: Win32.SafeHandles.SafeFileHandle, access: FileAccess, bufferSize: int) : unit
   (+0 other overloads)
FileStream(path: string, mode: FileMode, access: FileAccess, share: FileShare) : unit
   (+0 other overloads)
FileStream(handle: Win32.SafeHandles.SafeFileHandle, access: FileAccess, bufferSize: int, isAsync: bool) : unit
   (+0 other overloads)
FileStream(path: string, mode: FileMode, access: FileAccess, share: FileShare, bufferSize: int) : unit
   (+0 other overloads)
FileStream(path: string, mode: FileMode, access: FileAccess, share: FileShare, bufferSize: int, options: FileOptions) : unit
   (+0 other overloads)
FileStream(path: string, mode: FileMode, access: FileAccess, share: FileShare, bufferSize: int, useAsync: bool) : unit
   (+0 other overloads)
FileStream(path: string, mode: FileMode, rights: Security.AccessControl.FileSystemRights, share: FileShare, bufferSize: int, options: FileOptions) : unit
   (+0 other overloads)

type FileMode =
  | CreateNew = 1
  | Create = 2
  | Open = 3
  | OpenOrCreate = 4
  | Truncate = 5
  | Append = 6

Full name: System.IO.FileMode

field FileMode.Open = 3

val hashFunction : SHA512Managed

Multiple items
type SHA512Managed =
  inherit SHA512
  new : unit -> SHA512Managed
  member Initialize : unit -> unit

Full name: System.Security.Cryptography.SHA512Managed

--------------------
SHA512Managed() : unit

HashAlgorithm.ComputeHash(buffer: byte []) : byte []
HashAlgorithm.ComputeHash(inputStream: Stream) : byte []
HashAlgorithm.ComputeHash(buffer: byte [], offset: int, count: int) : byte []

type Convert =
  static val DBNull : obj
  static member ChangeType : value:obj * typeCode:TypeCode -> obj + 3 overloads
  static member FromBase64CharArray : inArray:char[] * offset:int * length:int -> byte[]
  static member FromBase64String : s:string -> byte[]
  static member GetTypeCode : value:obj -> TypeCode
  static member IsDBNull : value:obj -> bool
  static member ToBase64CharArray : inArray:byte[] * offsetIn:int * length:int * outArray:char[] * offsetOut:int -> int + 1 overload
  static member ToBase64String : inArray:byte[] -> string + 3 overloads
  static member ToBoolean : value:obj -> bool + 17 overloads
  static member ToByte : value:obj -> byte + 18 overloads
  ...

Full name: System.Convert

Convert.ToBase64String(inArray: byte []) : string
Convert.ToBase64String(inArray: byte [], options: Base64FormattingOptions) : string
Convert.ToBase64String(inArray: byte [], offset: int, length: int) : string
Convert.ToBase64String(inArray: byte [], offset: int, length: int, options: Base64FormattingOptions) : string

val hashAsync : bufferSize:int -> hashFunction:HashAlgorithm -> stream:Stream -> Async<string>

Full name: Script.hashAsync

val bufferSize : int

val hashFunction : HashAlgorithm

type HashAlgorithm =
  member CanReuseTransform : bool
  member CanTransformMultipleBlocks : bool
  member Clear : unit -> unit
  member ComputeHash : inputStream:Stream -> byte[] + 2 overloads
  member Dispose : unit -> unit
  member Hash : byte[]
  member HashSize : int
  member Initialize : unit -> unit
  member InputBlockSize : int
  member OutputBlockSize : int
  ...

Full name: System.Security.Cryptography.HashAlgorithm

val stream : Stream

type Stream =
  inherit MarshalByRefObject
  member BeginRead : buffer:byte[] * offset:int * count:int * callback:AsyncCallback * state:obj -> IAsyncResult
  member BeginWrite : buffer:byte[] * offset:int * count:int * callback:AsyncCallback * state:obj -> IAsyncResult
  member CanRead : bool
  member CanSeek : bool
  member CanTimeout : bool
  member CanWrite : bool
  member Close : unit -> unit
  member CopyTo : destination:Stream -> unit + 1 overload
  member Dispose : unit -> unit
  member EndRead : asyncResult:IAsyncResult -> int
  ...

Full name: System.IO.Stream

val hashBlock : (byte [] -> int -> Async<unit>)

val currentBlock : byte []

val count : int

val async : AsyncBuilder

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.async

val buffer : byte []

type Array =
  member Clone : unit -> obj
  member CopyTo : array:Array * index:int -> unit + 1 overload
  member GetEnumerator : unit -> IEnumerator
  member GetLength : dimension:int -> int
  member GetLongLength : dimension:int -> int64
  member GetLowerBound : dimension:int -> int
  member GetUpperBound : dimension:int -> int
  member GetValue : [<ParamArray>] indices:int[] -> obj + 7 overloads
  member Initialize : unit -> unit
  member IsFixedSize : bool
  ...

Full name: System.Array

val zeroCreate : count:int -> 'T []

Full name: Microsoft.FSharp.Collections.Array.zeroCreate

Multiple items
val byte : value:'T -> byte (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.byte

--------------------
type byte = Byte

Full name: Microsoft.FSharp.Core.byte

val readCount : int

member Stream.AsyncRead : count:int -> Async<byte []>
member Stream.AsyncRead : buffer:byte [] * ?offset:int * ?count:int -> Async<int>

HashAlgorithm.TransformFinalBlock(inputBuffer: byte [], inputOffset: int, inputCount: int) : byte []

val ignore : value:'T -> unit

Full name: Microsoft.FSharp.Core.Operators.ignore

HashAlgorithm.TransformBlock(inputBuffer: byte [], inputOffset: int, inputCount: int, outputBuffer: byte [], outputOffset: int) : int

property HashAlgorithm.Hash: byte []

val hashFileAsync : f:string -> Async<string>

Full name: Script.hashFileAsync

type File =
  static member AppendAllLines : path:string * contents:IEnumerable<string> -> unit + 1 overload
  static member AppendAllText : path:string * contents:string -> unit + 1 overload
  static member AppendText : path:string -> StreamWriter
  static member Copy : sourceFileName:string * destFileName:string -> unit + 1 overload
  static member Create : path:string -> FileStream + 3 overloads
  static member CreateText : path:string -> StreamWriter
  static member Decrypt : path:string -> unit
  static member Delete : path:string -> unit
  static member Encrypt : path:string -> unit
  static member Exists : path:string -> bool
  ...

Full name: System.IO.File

File.OpenRead(path: string) : FileStream