Command Line Flags in Wolfram Language

Here’s the translation of the Go code to Wolfram Language, along with explanations in Markdown format suitable for Hugo:

Command-line flags are a common way to specify options for command-line programs. For example, in `StringTake["hello", -2]` the `-2` is a command-line flag.

Wolfram Language doesn't have a built-in package for command-line flag parsing like Go's `flag` package. However, we can implement a simple command-line argument parser using pattern matching and association. Here's an example of how we might implement a similar functionality:

```wolfram
(* Define a function to parse command-line arguments *)
parseArgs[args_] := Module[{parsed = <||>},
  (* Parse each argument *)
  Scan[
    Function[arg,
      Switch[arg,
        _String?StringStartsQ["-"],
          (* Handle flags with values *)
          With[{split = StringSplit[StringDrop[arg, 1], "="]},
            If[Length[split] == 2,
              parsed[First[split]] = Last[split],
              (* Boolean flag *)
              parsed[StringDrop[arg, 1]] = True
            ]
          ],
        _,
          (* Positional argument *)
          AppendTo[parsed["tail"], arg]
      ]
    ],
    args
  ];
  (* Set default values for unspecified flags *)
  parsed["word"] = parsed["word"] /. Missing["KeyAbsent"] -> "foo";
  parsed["numb"] = ToExpression[parsed["numb"] /. Missing["KeyAbsent"] -> "42"];
  parsed["fork"] = TrueQ[parsed["fork"]];
  parsed["svar"] = parsed["svar"] /. Missing["KeyAbsent"] -> "bar";
  parsed["tail"] = parsed["tail"] /. Missing["KeyAbsent"] -> {};
  parsed
]

(* Main function *)
main[] := Module[{args, parsed},
  (* Get command-line arguments *)
  args = Rest[$CommandLine];
  
  (* Parse arguments *)
  parsed = parseArgs[args];
  
  (* Print parsed options and arguments *)
  Print["word: ", parsed["word"]];
  Print["numb: ", parsed["numb"]];
  Print["fork: ", parsed["fork"]];
  Print["svar: ", parsed["svar"]];
  Print["tail: ", parsed["tail"]];
]

(* Run the main function *)
main[]

To experiment with this command-line flags program, you’ll need to save it as a script (e.g., command-line-flags.wls) and run it from the command line using the wolframscript command.

Try out the script by giving it values for all flags:

$ wolframscript -file command-line-flags.wls -word=opt -numb=7 -fork -svar=flag
word: opt
numb: 7
fork: True
svar: flag
tail: {}

Note that if you omit flags, they automatically take their default values:

$ wolframscript -file command-line-flags.wls -word=opt
word: opt
numb: 42
fork: False
svar: bar
tail: {}

Trailing positional arguments can be provided after any flags:

$ wolframscript -file command-line-flags.wls -word=opt a1 a2 a3
word: opt
numb: 42
fork: False
svar: bar
tail: {a1, a2, a3}

Unlike Go’s flag package, this simple implementation doesn’t automatically generate help text or handle errors for undefined flags. You would need to implement these features manually if needed.

This example demonstrates how you can implement a basic command-line argument parsing system in Wolfram Language. While it’s not as feature-rich as Go’s flag package, it provides a similar functionality for handling command-line options in your Wolfram Language scripts.

Command Line Arguments in Wolfram Language

Context in Wolfram Language

Learn X By Example

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Command Line Flags in Wolfram Language