Nix JS

abstract class Package {
    abstract environment(): string[];
    abstract source(): string;
    abstract builder(): string;
    path(): string {
        return "bla";
    }
}

abstract class UnixPackage extends Package {
    abstract buildInputs(): Package[];

    environment(): string[] {
        let path = "";
        for (let buildInput of this.buildInputs()) {
            path += ":" + buildInput.path() + "/bin";
        }
        return ["path=" + path];
    }

    configure(): string {
        return "./configure";
    }

    build(): string {
        return "make";
    }

    install(): string {
        return "make install";
    }

    builder(): string {
        return this.configure() + "\n" +
               this.build() + "\n" +
               this.install();
    }
}

class FooPackage extends Package {
    environment(): string[] {
        return [];
    }

    source(): string {
        return "foo";
    }

    builder(): string {
        return "bla";
    }
}

class HelloPackage extends UnixPackage {
    buildInputs(): Package[] {
        return [
            new FooPackage(),
        ];
    }

    build(): string {
        return "foobar";
    }

    source(): string {
        return "bla";
    }
}

const package = new HelloPackage();

console.log(package.source());
console.log(package.environment());
console.log(package.builder());