Skip to content

Getting Started

This guide walks you through installing Mora, writing your first .mora file, compiling it into a patch file, and loading it into Skyrim. By the end you will have a working setup that applies patches at game load.

Prerequisites

Skyrim Special Edition (Steam). Mora targets SSE. The Game Pass version is not supported because it does not allow SKSE.

SKSE64. Mora's runtime DLL is loaded by SKSE. Download and install from skse.silverlock.org; match the version to your Skyrim build.

Address Library for SKSE Plugins. Install from Nexus Mods (mod 32444).

Mora itself — see below.

Building Mora

Mora is built from source. The compiler runs on Linux (or any POSIX host); the runtime DLL is produced by a cross-compiled build using clang-cl + lld-link and the Windows SDK via xwin. No Windows machine required.

Build dependencies

  • xmake — build system
  • clang-cl and lld-link — Clang's MSVC-compatible driver and linker
  • Windows SDK headers via xwin

Once those are on PATH:

git clone https://github.com/halgari/mora.git
cd mora

# Build the host-side compiler.
xmake build mora

# Build and test.
xmake build && xmake test

# The compiler binary is at build/linux/x86_64/release/mora

Add the mora binary to your PATH, or invoke it by its full path for the rest of this guide.

Your First .mora File

Create balance.mora anywhere:

namespace my_mod.balance

use form :as f

# All iron weapons get boosted damage.
iron_weapons(W):
    f/weapon(W)
    f/keyword(W, @WeapMaterialIron)
    => set form/damage(W, 20)

Line by line:

namespace my_mod.balance : Every file starts with a namespace declaration. Reverse-domain style is a good convention, but anything unique works.

use form :as f : Clojure-style namespace import. Aliases form to f so we can write f/weapon instead of form/weapon. :refer [...] is the other form, for bringing specific names in unqualified.

iron_weapons(W): : Rule head. W is a logic variable — unbound until the first clause binds it.

f/weapon(W) : Predicate. True when W is a weapon base record (a WEAP).

f/keyword(W, @WeapMaterialIron) : List-valued relation; in body position it's a query. @WeapMaterialIron is a compile-time EditorID reference — Mora resolves it against your ESPs and rejects the compile if the keyword isn't defined.

=> set form/damage(W, 20) : Head effect. form/damage is a countable<Int>; legal verbs are set, add, sub. set pins base damage to 20 on every matched weapon.

This rule is static: all body relations are in the form/* namespace, which is fully known at compile time. The compiler evaluates it completely and emits the resulting patches to the binary output; nothing about this rule runs at game time beyond applying the patches.

See language-guide.md for the full tour, and relations.md for the catalog of relations you can query.

Compiling

Point mora compile at your file and your Skyrim Data directory:

mora compile balance.mora --data-dir "/path/to/Skyrim Special Edition/Data"

On a typical Steam install on Linux that's ~/.steam/steam/steamapps/common/Skyrim Special Edition/Data.

Expected output:

  Mora v0.1.0

  [OK] Parsing 1 files
  [OK] Resolving 1 rules
  [OK] Type checking 1 rules
  [OK] 1 static, 0 dynamic
  [OK] 15 plugins, 3 relations -> 59522 facts
  [OK] Evaluating (.mora rules) done
  [OK] 200 patches -> mora_patches.bin (4.1 KB)
  [OK] Wrote MoraCache/mora_patches.bin

1 static, 0 dynamic : Phase classifier output. Unannotated rules whose bodies touch only static namespaces are static. Rules referencing ref/*, player/*, world/*, or event/* must be annotated maintain or on.

15 plugins, 3 relations -> 59522 facts : ESP load summary: how many plugins loaded, how many fact relations the compiler needed to extract, and the total fact count.

200 patches -> mora_patches.bin : The Datalog engine found 200 weapons that matched all clauses. Each one gets a 16-byte patch entry in the binary output.

When Mora detects your Skyrim install, mora_patches.bin is written directly to <Data>/SKSE/Plugins/ — no copy step needed. Otherwise it falls back to MoraCache/mora_patches.bin relative to your sources. Override either path with --output DIR.

If you'd like to see exactly what patches would be produced without touching the filesystem, use mora inspect.

Warning

If you see form not found: @WeapMaterialIron, the keyword's EditorID isn't present in any loaded plugin. Double-check the spelling and make sure the plugin that defines it is in your Data directory.

Deploying

With auto-detection (the default when you run mora compile with no flags), mora_patches.bin already lands in <Data>/SKSE/Plugins/. You only need to deploy the runtime DLL:

Data/SKSE/Plugins/
  mora_patches.bin     <-- written by `mora compile` directly
  MoraRuntime.dll      <-- from the xmake build

Launch the game through SKSE (via skse64_loader.exe or your mod manager's SKSE option). Launching plain SkyrimSE.exe will not load SKSE plugins.

Mod Organizer 2 users

Deploy both files into a mod folder under the same SKSE/Plugins/ path. MO2 will virtualize them into the Data directory automatically.

Verifying

On load, the runtime writes a log file at:

Data/SKSE/Plugins/MoraRuntime.log

You should see something like:

[Mora] mmap'd mora_patches.bin (4.1 KB)
[Mora] applied 200 patches in 0.42 ms
[Mora] dynamic rules: 0 (nothing to register)

If the file is missing, SKSE didn't load the plugin. Check skse64.log in the same folder for SKSE's own diagnostics.

Next Steps

  • Language Guide — negation, disjunction, arithmetic, maintain and on rules, namespaces, :keyword tag values.
  • Examples — annotated .mora files including the bandit bounty capstone.
  • How Mora Works — the architectural overview: why Mora splits rules across static/maintain/on, and how the runtime loads the patch file.
  • Relation Reference — the full inventory of built-in relations, auto-generated from the YAML declarations.