Concatenating PDFs With F#

Concatenating PDFs with F#

At work today I needed to combine some pdfs together. Since I didn't have a license to Adobe Acrobat, nor MacOS (which has this functionality built in natively), I needed a quick solution using a third party library, in this case I used PdfSharp. I also figured a quick F# script would do the trick. So below is what I whipped up in about 20 minutes to get the job done and have a reuseable solution in the future if the need arises.

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#r "C:/Shared Resources/PdfSharp/PDFsharp.1.50.5147/lib/net20/PdfSharp.dll"

open System.IO
open PdfSharp.Pdf
open PdfSharp.Pdf.IO

let sourceDir = "C:/Users/Jason/Documents" // Or wherever your PDFs are
let targetFileName = Path.Combine(sourceDir, "Result.pdf") // Or whatever you want your output called
let pdfFiles = Directory.GetFiles(sourceDir, "*.pdf") |> Array.toList

// Gets all of the pages for a PDF document
let getPages (sourceFileName : string) =
    use source = PdfReader.Open(sourceFileName, PdfDocumentOpenMode.Import)
    [
      for i = 0 to source.PageCount - 1 do
        yield source.Pages.[i]
    ]

// Gets all of the pages for all of the PDFs
let getAllPages =
    List.collect getPages pdfFiles

// Adds all the pages to one document
let createDocFromPages pages =
    let targetDoc = new PdfDocument()  
    pages |> List.iter (targetDoc.Pages.Add >> ignore)
    targetDoc

// Creates the document and writes output to disk
let concatDocs =  
    let doc = createDocFromPages getAllPages
    doc.Save targetFileName
    doc.Dispose()

// Kicks it all off
concatDocs

namespace System

namespace System.IO

namespace PdfSharp

namespace PdfSharp.Pdf

namespace PdfSharp.Pdf.IO

val sourceDir : string

Full name: concatenatingpdfswithfsharp.sourceDir

val targetFileName : string

Full name: concatenatingpdfswithfsharp.targetFileName

type Path =
  static val DirectorySeparatorChar : char
  static val AltDirectorySeparatorChar : char
  static val VolumeSeparatorChar : char
  static val InvalidPathChars : char[]
  static val PathSeparator : char
  static member ChangeExtension : path:string * extension:string -> string
  static member Combine : [<ParamArray>] paths:string[] -> string + 3 overloads
  static member GetDirectoryName : path:string -> string
  static member GetExtension : path:string -> string
  static member GetFileName : path:string -> string
  ...

Full name: System.IO.Path

Path.Combine([<System.ParamArray>] paths: string []) : string
Path.Combine(path1: string, path2: string) : string
Path.Combine(path1: string, path2: string, path3: string) : string
Path.Combine(path1: string, path2: string, path3: string, path4: string) : string

val pdfFiles : string list

Full name: concatenatingpdfswithfsharp.pdfFiles

type Directory =
  static member CreateDirectory : path:string -> DirectoryInfo + 1 overload
  static member Delete : path:string -> unit + 1 overload
  static member EnumerateDirectories : path:string -> IEnumerable<string> + 2 overloads
  static member EnumerateFileSystemEntries : path:string -> IEnumerable<string> + 2 overloads
  static member EnumerateFiles : path:string -> IEnumerable<string> + 2 overloads
  static member Exists : path:string -> bool
  static member GetAccessControl : path:string -> DirectorySecurity + 1 overload
  static member GetCreationTime : path:string -> DateTime
  static member GetCreationTimeUtc : path:string -> DateTime
  static member GetCurrentDirectory : unit -> string
  ...

Full name: System.IO.Directory

Directory.GetFiles(path: string) : string []
Directory.GetFiles(path: string, searchPattern: string) : string []
Directory.GetFiles(path: string, searchPattern: string, searchOption: SearchOption) : string []

module Array

from Microsoft.FSharp.Collections

val toList : array:'T [] -> 'T list

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

val getPages : sourceFileName:string -> PdfPage list

Full name: concatenatingpdfswithfsharp.getPages

val sourceFileName : string

Multiple items
val string : value:'T -> string

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

--------------------
type string = System.String

Full name: Microsoft.FSharp.Core.string

val source : PdfDocument

type PdfReader =
static member Open : path:string -> PdfDocument + 10 overloads
static member TestPdfFile : path:string -> int + 2 overloads

Full name: PdfSharp.Pdf.IO.PdfReader

PdfReader.Open(stream: Stream) : PdfDocument
   (+0 other overloads)
PdfReader.Open(path: string) : PdfDocument
   (+0 other overloads)
PdfReader.Open(stream: Stream, openmode: PdfDocumentOpenMode) : PdfDocument
   (+0 other overloads)
PdfReader.Open(path: string, password: string) : PdfDocument
   (+0 other overloads)
PdfReader.Open(path: string, openmode: PdfDocumentOpenMode) : PdfDocument
   (+0 other overloads)
PdfReader.Open(stream: Stream, password: string, openmode: PdfDocumentOpenMode) : PdfDocument
   (+0 other overloads)
PdfReader.Open(stream: Stream, openmode: PdfDocumentOpenMode, passwordProvider: PdfPasswordProvider) : PdfDocument
   (+0 other overloads)
PdfReader.Open(path: string, password: string, openmode: PdfDocumentOpenMode) : PdfDocument
   (+0 other overloads)
PdfReader.Open(path: string, openmode: PdfDocumentOpenMode, provider: PdfPasswordProvider) : PdfDocument
   (+0 other overloads)
PdfReader.Open(stream: Stream, password: string, openmode: PdfDocumentOpenMode, passwordProvider: PdfPasswordProvider) : PdfDocument
   (+0 other overloads)

type PdfDocumentOpenMode =
  | Modify = 0
  | Import = 1
  | ReadOnly = 2
  | InformationOnly = 3

Full name: PdfSharp.Pdf.IO.PdfDocumentOpenMode

field PdfDocumentOpenMode.Import = 1

val i : int

property PdfDocument.PageCount: int

property PdfDocument.Pages: PdfPages

val getAllPages : PdfPage list

Full name: concatenatingpdfswithfsharp.getAllPages

Multiple items
module List

from Microsoft.FSharp.Collections

--------------------
type List<'T> =
  | ( [] )
  | ( :: ) of Head: 'T * Tail: 'T list
  interface IEnumerable
  interface IEnumerable<'T>
  member GetSlice : startIndex:int option * endIndex:int option -> 'T list
  member Head : 'T
  member IsEmpty : bool
  member Item : index:int -> 'T with get
  member Length : int
  member Tail : 'T list
  static member Cons : head:'T * tail:'T list -> 'T list
  static member Empty : 'T list

Full name: Microsoft.FSharp.Collections.List<_>

val collect : mapping:('T -> 'U list) -> list:'T list -> 'U list

Full name: Microsoft.FSharp.Collections.List.collect

val createDocFromPages : pages:PdfPage list -> PdfDocument

Full name: concatenatingpdfswithfsharp.createDocFromPages

val pages : PdfPage list

val targetDoc : PdfDocument

Multiple items
type PdfDocument =
  inherit PdfObject
  new : unit -> PdfDocument + 2 overloads
  member AcroForm : PdfAcroForm
  member AddPage : unit -> PdfPage + 1 overload
  member CanSave : message:string -> bool
  member Close : unit -> unit
  member CustomValues : PdfCustomValues with get, set
  member Dispose : unit -> unit
  member FileSize : int64
  member Flatten : unit -> unit
  member FullPath : string
  ...

Full name: PdfSharp.Pdf.PdfDocument

--------------------
PdfDocument() : unit
PdfDocument(filename: string) : unit
PdfDocument(outputStream: Stream) : unit

val iter : action:('T -> unit) -> list:'T list -> unit

Full name: Microsoft.FSharp.Collections.List.iter

PdfPages.Add() : PdfPage
PdfPages.Add(page: PdfPage) : PdfPage

val ignore : value:'T -> unit

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

val concatDocs : unit

Full name: concatenatingpdfswithfsharp.concatDocs

val doc : PdfDocument

PdfDocument.Save(stream: Stream) : unit
PdfDocument.Save(path: string) : unit
PdfDocument.Save(stream: Stream, closeStream: bool) : unit

PdfDocument.Dispose() : unit