Erlang’s epp preprocesses Erlang source during compilation; Elixir’s interoperability with Erlang means Elixir code can use Erlang modules on the Erlang VM. Those are related, but not the same: sharing a runtime does not by itself establish that Elixir source can consume every Erlang preprocessor directive, .hrl file, or macro.
What the Erlang preprocessor does
Erlang’s epp is a compile-time source-processing step. It handles file inclusion, macro expansion, and conditional compilation before the source is parsed. It is not a runtime bridge between Erlang and Elixir. The Erlang epp reference describes this role.
Macros and included headers
An Erlang -define directive creates a macro, and ?Name invokes it. Definitions must appear before use, and expansion happens during compilation. Shared definitions, including records and macros, are commonly stored in header files with the .hrl extension.
The -include directive inserts a file at the directive’s location. -include_lib resolves a file from an application’s library directory. Include search paths and conditional-compilation directives affect which source is included and compiled. Consult the Erlang macro and preprocessor documentation for the compiler’s exact rules.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Inspecting preprocessed output
To produce a listing after preprocessing and parse transforms, Erlang’s compiler supports the 'P' option. For example, compile:file("my_module.erl", ['P']). This can help diagnose which include files, macro expansions, or conditional branches reached the later compiler stages.
What Elixir interoperability with Erlang means
Elixir runs on the Erlang virtual machine and is compatible with OTP. Elixir applications can call Erlang modules, making Erlang’s ecosystem available without making the two languages’ source syntax identical. The Elixir team’s design-goals article explains the same-VM relationship.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Interoperability can also mean crossing a different boundary—for example, calling native code, communicating with another operating-system process, or sending messages between runtime nodes. Those choices differ in call style, isolation, and operational risk.
| Mechanism | Boundary and communication | Key trade-off |
|---|---|---|
| Calling an Erlang module | Same Erlang VM; direct module/function calls | Language-level integration. It does not mean Erlang preprocessing syntax is accepted in Elixir source. |
| NIF | Native code called directly within the VM process and memory space | Useful for performance-critical or system-level code, but faulty native code can compromise VM stability and error-handling guarantees. |
| Port | Communication with a separate operating-system process, typically through process I/O | Process separation provides isolation from the VM, with the operational work of managing a separate process and its communication. |
| Distributed node | Communication across runtime nodes through networked message passing | Adds runtime and network boundaries to operations and failure handling. |
In “Interoperability in 2025: beyond the Erlang VM,” authors Wojtek Mach and José Valim write: “NIFs allow us to write performance-critical or system-level code and call it directly from Erlang and Elixir as if it were a regular function.” The same article cautions that NIFs run in the VM process, so native-code faults can affect VM stability.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Can Elixir source use Erlang .hrl files and macros?
Do not assume the answer from the runtime relationship alone. Erlang documentation specifies how Erlang’s compiler handles .hrl files and preprocessor macros; Elixir documentation establishes Elixir’s access to Erlang modules. Those facts do not, by themselves, settle whether a particular Elixir compiler version or build setup can consume an Erlang header or macro, or under what rules.
For a project that depends on this boundary, verify the exact Elixir release, compiler feature, and build configuration against its primary documentation or a minimal example using that toolchain. Establish which compiler processes the file and whether the required directives are supported. Do not treat an Erlang function call from Elixir as evidence that Erlang source directives work in Elixir code.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Check Elixir and OTP compatibility
Compatibility is release-specific. The Elixir documentation retrieved on October 4, 2026 lists Elixir v1.20.4 as stable and Erlang/OTP 27, 28, and 29 as supported. The Elixir installation page says Elixir v1.20.4 requires OTP 27.0 or later. Check the current Elixir documentation and installation guidance before choosing versions, because support changes over time.
Documentation interoperability has also developed over time. The Elixir v1.7 release article says that release implemented EEP 48, an effort to make documentation interoperable across languages on the Erlang VM. The v1.11 release article noted that IEx could display Erlang module documentation with Erlang/OTP 23 or later when the Erlang modules had documentation chunks. These are historical release details, not guarantees that every current project has the required documentation available: Elixir v1.7 release and Elixir v1.11 release.
Recommended Free Tools
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
