Xml in Idris

Here’s the translation of the XML example from Go to Idris:

Our first example demonstrates how to work with XML in Idris. We’ll use the Text.XML module for XML processing.

import Text.XML
import Data.String

-- Plant will be mapped to XML. We use record syntax to define the structure.
-- The `xmlName` field is used to specify the XML element name for this record.
record Plant where
  constructor MkPlant
  xmlName : Maybe String
  id : Int
  name : String
  origin : List String

-- Define a custom Show instance for Plant
Show Plant where
  show (MkPlant _ id name origin) = 
    "Plant id=" ++ show id ++ ", name=" ++ name ++ ", origin=" ++ show origin

-- Main function
main : IO ()
main = do
  -- Create a Plant instance
  let coffee = MkPlant (Just "plant") 27 "Coffee" ["Ethiopia", "Brazil"]

  -- Convert Plant to XML
  let xmlStr = maybe "" id $ toXML coffee

  -- Print the XML
  putStrLn xmlStr

  -- Print XML with header
  putStrLn $ "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" ++ xmlStr

  -- Parse XML back to Plant
  case parseXML xmlStr of
    Right doc => do
      case fromXML {a = Plant} doc of
        Just p => putStrLn $ show p
        Nothing => putStrLn "Failed to parse XML to Plant"
    Left err => putStrLn $ "XML parsing error: " ++ err

  -- Create another Plant instance
  let tomato = MkPlant (Just "plant") 81 "Tomato" ["Mexico", "California"]

  -- Define a Nesting structure
  record Nesting where
    constructor MkNesting
    xmlName : Maybe String
    plants : List Plant

  -- Create a Nesting instance
  let nesting = MkNesting (Just "nesting") [coffee, tomato]

  -- Convert Nesting to XML
  let nestingXml = maybe "" id $ toXML nesting

  -- Print the nested XML
  putStrLn nestingXml

In this Idris example, we’re using the Text.XML module to work with XML. Here’s a breakdown of what’s happening:

We define a Plant record that represents our data structure. The xmlName field is used to specify the XML element name.
We implement a custom Show instance for Plant to provide a string representation.
In the main function, we create a Plant instance for coffee and convert it to XML using the toXML function.
We print the XML representation, both with and without the XML header.
We then demonstrate parsing the XML back into a Plant instance using parseXML and fromXML.
We create another Plant instance for tomato and define a Nesting record to demonstrate nested XML structures.
Finally, we create a Nesting instance with both plants and convert it to XML.

Note that Idris’s XML handling might be less feature-rich compared to Go’s encoding/xml package. The exact behavior and available features may vary depending on the specific XML library used in Idris.

To run this program, save it as xml_example.idr and use the Idris compiler:

$ idris xml_example.idr -o xml_example
$ ./xml_example

This will compile and run the Idris program, displaying the XML output and parsed data.

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Xml in Idris