1 files changed, 25 insertions, 0 deletions
diff --git a/lib/process/env.ts b/lib/process/env.ts
new file mode 100644
index 0000000..f59fadf
--- /dev/null
+++ b/lib/process/env.ts
@@ -0,0 +1,25 @@
+import { IOptional, Either, Optional, type IEither, type ObjectFromList } from '@emprespresso/pengueno';
+
+// type safe environment variables
+
+export const getEnv = (name: string): IOptional<string> => Optional.from(process.env[name]);
+
+export const getRequiredEnv = <V extends string>(name: V): IEither<Error, string> =>
+    Either.fromFailable(() => getEnv(name).get()).mapLeft(
+        () => new Error(`environment variable "${name}" is required D:`),
+    );
+
+export const getRequiredEnvVars = <V extends string>(vars: Array<V>): IEither<Error, ObjectFromList<typeof vars>> => {
+    type Environment = ObjectFromList<typeof vars>;
+    const emptyEnvironment = Either.right<Error, Environment>(<Environment>{});
+    const addTo = (env: Environment, key: V, val: string) =>
+        <Environment>{
+            ...env,
+            [key]: val,
+        };
+    return vars.reduce(
+        (environment, key) =>
+            environment.joinRight(getRequiredEnv(key), (value, environment) => addTo(environment, key, value)),
+        emptyEnvironment,
+    );
+};