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https://github.com/anler/bs-getenv
ReasonML/BuckleScript PPX for embedding env variables
https://github.com/anler/bs-getenv
environment-variables ppx ppx-rewriter reasonml
Last synced: about 2 months ago
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ReasonML/BuckleScript PPX for embedding env variables
- Host: GitHub
- URL: https://github.com/anler/bs-getenv
- Owner: anler
- License: mit
- Created: 2020-05-14T13:08:04.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2020-06-24T13:37:48.000Z (over 4 years ago)
- Last Synced: 2024-04-25T11:22:04.875Z (8 months ago)
- Topics: environment-variables, ppx, ppx-rewriter, reasonml
- Language: Shell
- Size: 876 KB
- Stars: 25
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# bs-getenv
 [](https://www.npmjs.com/package/bs-getenv)
PPX for [ReasonML](https://reasonml.github.io) / [BuckleScript](https://bucklescript.github.io) for embedding
environment variables in the code.
## Installation
Get the package:
```shell
# yarn
yarn add bs-getenv
# or npm
npm install --save bs-getenv
```
Then add it to `bsconfig.json`:
```json
"ppx-flags": ["bs-getenv/ppx"]
```
## Usage
### `%getenv ...`
#### With a default value
Usage: `[%getenv VAR_NAME; defaultValue]`, where:
- The result type will be `string`
- `defaultValue` can be any expression of type `string`
#### Without a default value
Usage: `[%getenv VAR_NAME]`, where:
- The result type will be `option(string)`.
### `%getenv.exn ...`
Usage: `[%getenv.exn VAR_NAME]`, where:
- The result type will be `string`
- Useful in those cases where the application absolutely needs an env variable to exist (e.g.: app secrets)
- If `VAR_NAME` env var does not exist, it will fail **at compile time** with the message: `%getenv environment variable not found: VAR_NAME`
### `switch%getenv ...`
#### With a default value (exhaustive pattern matching)
Usage:
```reason
switch%getenv (VAR_NAME) {
| "" => ...
| _ => ...default
}
```
where:
- The result type will be the type of the cases
#### Without a default value (non-exhaustive pattern matching)
Usage:
```reason
switch%getenv (VAR_NAME) {
| "" => ...
}
```
where:
- The result type will be `option(t)` where `t` is the type of the cases
## Example
```reason
let getDefaultValue = () => "Some other value";
let var1: string = [%getenv SOME_VAR_THAT_DOESNT_EXIST; getDefaultValue()];
let var2: string = [%getenv USER; "default value"];
let var3: option(string) = [%getenv HOME];
let var4: option(string) = [%getenv SOME_VAR_THAT_DOESNT_EXIST];
let var5: bool =
switch%getenv (USER) {
| "anler" => true
| _ => false
};
let var6: option(bool) =
switch%getenv (USER) {
| "anler" => true
};
```
## Developing
Clone repo and install deps:
```shell
esy install
yarn install
```
Build ppx:
```shell
esy build
```
To explore generated output, run `yarn build` and look the compiled file `test/Test.bs.js`.
## TODO
- [x] Just get env variables
- [x] Support switch cases
- [x] Better error reporting
- [ ] Support switch guards and variables