Strategy pattern in functional programming

Question

I am trying to write a Strategy design pattern example in the functional programming language ( not purely functional, no objects, no function overloading) using the example mentioned on Java DZone.

Though I understand that a lot of functionality comes out of the box in the functional programming language.

Am I missing anything here in terms of the design pattern concept?

: is the assignment operator.

File FileCompressor

strategy:`noOp;

setCompressionAlgo:{[algo]
    strategy:algo
}

compressFiles:{[filesList]
    strategy[filesList]
 }

File ZipCompressor

zipCompress:{[fileList]
  //compress each file using the zip compression
 }

File RarCompressor

rarCompress:{[fileList]
  //compress each file using the rar compression
 }

File Client

start:{[path]
    filesList:getFiles[path];
    setCompressionAlgo[zipCompress];
    compressFiles[fileList]
 }

Answer 1

You usually wouldn't make the strategy a global (mutable) variable. You can simplify your example to

start: {[path]
    compressFiles: zipCompress;
    // change to
    // compressFiles: rarCompress
    // to use a different strategy

    // apply the strategy:
    compressFiles[fileList1]
    compressFiles[fileList2]
}