How to declare 'main' in a hy program

Question

As per the official docs, I should be able to to use

def main [ &rest _ ]

I tried the example in a let block :

(import argparse) 
(require [hy.contrib.walk [let]]) 
(def main [&rest _]
   (let [parser (argparse.ArgumentParser)]
     (.add-argument parser "STRING"
       :help "string to replicate")
     (.add-argument parser "-n" :type int :default 3
       :help "number of copies")
     (setv args (parser.parse_args))
     (print (* args.STRING args.n))
     ))

But I see the following error :

... trace
NameError: name 'hyx_def' is not defined

Oddly enough, the codeblock which prints the string 'n' times, works fine. The error appears at the end however.

As per this link : https://github.com/hylang/hy/pull/1483 , def has been completely removed.

So what should I use to declare a main function ?

Not an expert on hy myself, but on the link you provided they are saying to replace `def` with `setv`. Have you tried that? — Not a real meerkat, Nov 16 '20 at 12:48
yes, that doesnt even parse. I think setv is a variable assignment form, where as def main used to be a macro. — dedupe, Nov 16 '20 at 13:58
Where does `def main [ &rest _ ]` appear in the documentation? That's a fairly extreme typo. — Kodiologist, Nov 16 '20 at 14:11

score 0 · Accepted Answer · answered Nov 17 '20 at 03:44

defmain

is the correct form. The below works :

(import argparse) 
(require [hy.contrib.walk [let]]) 
(defmain [&rest _]
   (let [parser (argparse.ArgumentParser)]
     (.add-argument parser "STRING"
       :help "string to replicate")
     (.add-argument parser "-n" :type int :default 3
       :help "number of copies")
     (setv args (parser.parse_args))
     (print (* args.STRING args.n))
     ))

How to declare 'main' in a hy program

1 Answers1