load-env

Load environment variables from a file.

https://github.com/pbrisbin/load-env#readme

LTS Haskell 23.19:	0.2.1.0
Stackage Nightly 2025-04-30:	0.2.1.0
Latest on Hackage:	0.2.1.0

See all snapshots load-env appears in

BSD-3-Clause licensed and maintained by Pat Brisbin

This version can be pinned in stack with:load-env-0.2.1.0@sha256:17628d397cf7ba6af9bf103c2c3592bb246e2ad58bd019cc5071c654887b1083,1866

Module documentation for 0.2.1.0

LoadEnv
- LoadEnv.Parse

Depends on 4 packages(full list with versions):

base, directory, filepath, parsec

Used by 1 package in lts-14.27(full list with versions):

yesod-auth-oauth2

load-env

This is effectively a port of dotenv, whose README explains it best:

Storing configuration in the environment is one of the tenets of a twelve-factor app. Anything that is likely to change between deployment environments–such as resource handles for databases or credentials for external services–should be extracted from the code into environment variables.

But it is not always practical to set environment variables on development machines or continuous integration servers where multiple projects are run. dotenv loads variables from a .env file into ENV when the environment is bootstrapped.

This library exposes functions for doing just that.

Usage

import LoadEnv
import System.Environment (lookupEnv)

main :: IO ()
main = do
    loadEnv

    print =<< lookupEnv "FOO"

% cat .env
FOO=bar
% runhaskell main.hs
Just "bar"

Development & Test

stack setup
stack build --pedantic --test

CHANGELOG | LICENSE

Changes

Unreleased

None

v0.2.1.0

Don’t override values already set in the environment

Given a hypothetical program load-env, which uses one of our loadEnv functions on stdin:

Previously,
```
FOO=bar load-env <<EOM
FOO=bat
EOM
```
would override FOO to bat when load-env ran. But now, it will see FOO is already bar and leave it.

This is better behavior under the assumption that a .env file is meant to specify defaults in the case of nothing explicit. When there are explicit values in the environment, it’s most likely that our user indeed wants them respected.