Emojis only print as "?"

#1

I have the following simple haskell file (with some nix-shell goodness):

#! /usr/bin/env nix-shell
#! nix-shell --pure -i runghc -p ghc

main = putStrLn "🎉"

but when I run it:

❯ ./emoji.hs 
?

I also tried the demo code for the emoji package (https://hackage.haskell.org/package/emoji), and it’s the same issue. Am I missing something here? What should I do in order to get emojis printing correctly?

#2

works on my machine (without nix stuff). Maybe it’s your terminal or locale settings?

1 Like
#3

Hmm, interesting… I tried a python script with an emoji in the same terminal and it works without issue. Perhaps it’s a nix issue?

#4

Maybe check the locale first

#5

This seems to happen because nix-shell --pure removes the locale env.
You need both an environment variable like LC_ALL and the locale archive provided by the glibc, e.g. using this command instead: nix-shell --pure -p glibcLocale -i "env LC_ALL=en_US.UTF-8 runghc" -p ghc

3 Likes
#6

Nice! The --pure does seem to be the issue. I’m a little confused though because

#!/usr/bin/env nix-shell
(*
#!nix-shell --pure -i ocaml -p ocaml
*)
print_string "Hello world! 🚀 \n";;

and

#!/usr/bin/env nix-shell
#!nix-shell --pure -i python3 -p python3
print("🚀")

both work fine…

#7

Is this on non-NixOS? There was an issue about how locales work with relation to non-NixOS and GHC:

#8

I’m running on NixOS, but I could imagine that the issues might be related somehow.