Nix-shell as #! interpreter for runghc

Question

I am trying to use nix-shell as #! wrapper for runghc as indicated in the man page. But he cannot find the library. In the following example, cutting from manpage

#! /usr/bin/env nix-shell
#! nix-shell -i runghc -p haskellPackages.HTTP

import Network.HTTP

main = return ()

I get the following result:

[~:0]$ ./nixshelltest 

nixshelltest:4:1: error:
    Failed to load interface for ‘Network.HTTP’
    Use -v to see a list of the files searched for.
[~:1]$ 

in my opinion, exactly what nix-shell -p should avoid.

Am I doing something wrong skipping a point or is there a mistake? This is on both the nixOS 17.03 host and the host running nix 17.09 on top of Ubuntu.

Thank,

Answer 1

There is no step in the environment you use to run the script. He received the GHC and the HTTP packet, but the compiler does not know about the packet.

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, , "" GHC, , . GHC, , GHC. , , , - GHC, .

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:

#! nix-shell -i runghc -p 'ghc.withPackages (ps: [ ps.HTTP ])'

ghc HTTP; ghc.withPackages nix, GHC, HTTP Haskell. "" GHC , HTTP .

Haskell (, nix-shell, , ), withPackages, , , - . , , nix GHC .