Fix equality of derived units and quantities to not depend on unit instance identity

.claude/settings.json

@@ -0,0 +1,26 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(markdownlint *)",
+      "Bash(shellcheck *)",
+      "Bash(yamllint *)",
+      "Bash(git add *)",
+      "Bash(git blame *)",
+      "Bash(git branch)",
+      "Bash(git checkout *)",
+      "Bash(git config --get *)",
+      "Bash(git describe *)",
+      "Bash(git diff *)",
+      "Bash(git fetch *)",
+      "Bash(git grep *)",
+      "Bash(git log *)",
+      "Bash(git ls-files *)",
+      "Bash(git remote *)",
+      "Bash(git show *)",
+      "Bash(git stash list)",
+      "Bash(git status *)",
+      "Bash(git tag *)",
+      "WebFetch"
+    ]
+  }
+}

.devcontainer/.env.example

@@ -0,0 +1,10 @@
+# Copy this file to .devcontainer/.env and adjust the values below.
+
+# Folder containing your other projects, mounted read-only at /reference.
+# Defaults to this repository when unset.
+REFERENCE_PROJECTS_DIR=/path/to/your/projects
+
+# Timezone for the container. Defaults to UTC when unset.
+# Applied at container start, so changing it needs no image rebuild.
+TZ=UTC
+

.devcontainer/Dockerfile

@@ -0,0 +1,25 @@
+FROM mcr.microsoft.com/devcontainers/javascript-node:24-trixie
+
+# Install dependencies
+RUN apt-get update \
+  && apt-get install --yes --no-install-recommends \
+    shellcheck \
+    yamllint \
+  && rm --recursive --force /var/lib/apt/lists/*
+
+# Create the shell history mount point up front so the named volume inherits
+# node ownership instead of being created as root.
+RUN mkdir --parents /commandhistory \
+  && chown node:node /commandhistory
+
+USER node
+WORKDIR /home/node
+
+# Install markdownlint-cli for linting docs
+RUN npm install --global markdownlint-cli@0.48.0
+
+# Install Claude stable (lands in /home/node/.local/bin, already on PATH)
+RUN curl --fail --silent --show-error \
+  --location https://claude.ai/install.sh --output /tmp/install-claude.sh \
+  && bash /tmp/install-claude.sh stable \
+  && rm /tmp/install-claude.sh

.devcontainer/devcontainer.json

@@ -0,0 +1,21 @@
+{
+  "name": "Aconcagua",
+  "dockerComposeFile": "docker-compose.yml",
+  "service": "aconcagua-tools",
+  "workspaceFolder": "/workspace",
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "anthropic.claude-code",
+        "DavidAnson.vscode-markdownlint",
+        "mhutchie.git-graph",
+        "timonwong.shellcheck",
+        "fnando.linter"
+      ],
+      "settings": {
+        "editor.formatOnSave": true
+      }
+    }
+  },
+  "remoteUser": "node"
+}

.devcontainer/docker-compose.yml

@@ -0,0 +1,25 @@
+services:
+  aconcagua-tools:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    volumes:
+      - ..:/workspace
+      - claude-code-bashhistory:/commandhistory
+      - claude-code-config:/home/node/.claude
+      # Read-only access to other projects for reference.
+      # Set REFERENCE_PROJECTS_DIR in .devcontainer/.env to the folder
+      # containing your projects; it is mounted at /reference.
+      # Defaults to this repository when unset so a rebuild never fails.
+      - ${REFERENCE_PROJECTS_DIR:-..}:/reference:ro
+    environment:
+      # Set TZ in .devcontainer/.env to your local timezone
+      TZ: ${TZ:-UTC}
+      # Link the shell history to the persistent volume
+      HISTFILE: /commandhistory/.bash_history
+    # Keep the container running so the devcontainer can attach to it
+    command: sleep infinity
+
+volumes:
+  claude-code-bashhistory:
+  claude-code-config:

.gitignore

@@ -1 +1,7 @@
 .DS_Store
+
+# Environment variables
+.devcontainer/.env
+
+# Claude Code local settings (per-machine overrides, not shared)
+.claude/settings.local.json

source/Aconcagua-Quantitative-Analysis-Tests/AccountDimensionTest.class.st

@@ -19,8 +19,40 @@ AccountDimensionTest >> testComparison [
     deny: dimension equals: ( AccountDimension on: 'ARS' symbol: '$' )
 ]
 
+{ #category : 'tests' }
+AccountDimensionTest >> testComparisonOfDerivedDimensions [
+
+  | usd btc rate equalRate |
+  usd := AccountDimension on: 'USD' symbol: '$'.
+  btc := AccountDimension on: 'BTC' symbol: '₿'.
+  rate := usd / btc.
+  equalRate := ( AccountDimension on: usd reference symbol: usd symbol )
+               / ( AccountDimension on: btc reference symbol: btc symbol ).
+
+  self
+    assert: rate equals: equalRate;
+    assert: rate hash equals: equalRate hash;
+    assert: ( equalRate occurrencesOf: usd ) equals: 1;
+    assert: ( equalRate occurrencesOf: btc ) equals: -1
+]
+
 { #category : 'tests' }
 AccountDimensionTest >> testPrintString [
 
   self assert: ( AccountDimension on: 'USD' symbol: '$' ) printString equals: '$'
 ]
+
+{ #category : 'tests' }
+AccountDimensionTest >> testProductWithEqualDimension [
+
+  | usd btc equivalentToUsd |
+  usd := AccountDimension on: 'USD' symbol: '$'.
+  btc := AccountDimension on: 'BTC' symbol: '₿'.
+  equivalentToUsd := AccountDimension on: usd reference symbol: usd symbol.
+
+  self
+    assert: ( usd / btc * equivalentToUsd ) printString equals: '$²₿⁻¹';
+    assert: usd / btc * equivalentToUsd equals: usd * usd / btc;
+    assert: ( usd / equivalentToUsd * btc ) printString equals: '₿';
+    assert: usd / equivalentToUsd * btc equals: btc
+]

source/Aconcagua-Quantitative-Analysis-Tests/UnitOfAccountTest.class.st

@@ -128,6 +128,24 @@ UnitOfAccountTest >> testCommensurability [
     deny: ( usdt isCommensurableWith: centisecond )
 ]
 
+{ #category : 'tests' }
+UnitOfAccountTest >> testCommensurabilityOfDerivedUnitsBuiltFromEqualUnits [
+
+  | rate equalRate |
+  rate := usd / btc.
+  equalRate := ( UnitOfAccount on: 'USD' symbol: '$' ) / ( UnitOfAccount on: 'BTC' symbol: '₿' ).
+
+  self
+    assert: rate equals: equalRate;
+    assert: rate hash equals: equalRate hash;
+    assert: rate dimension equals: equalRate dimension;
+    assert: rate dimension hash equals: equalRate dimension hash;
+    assert: ( rate isCommensurableWith: equalRate );
+    assert: ( equalRate isCommensurableWith: rate );
+    assert: 100 * rate equals: 100 * equalRate;
+    assert: ( 100 * rate ) + ( 100 * equalRate ) equals: 200 * rate
+]
+
 { #category : 'tests' }
 UnitOfAccountTest >> testComparison [
 
@@ -221,6 +239,21 @@ UnitOfAccountTest >> testQuantityAddition [
     assert: ( oneThousandUSDT + oneHundredUSDT ) printString equals: '1100 ₮'
 ]
 
+{ #category : 'tests' }
+UnitOfAccountTest >> testQuantityMultiplication [
+
+  | oneBitcoin sixtyThousandUsdt |
+  oneBitcoin := 1 * btc.
+  sixtyThousandUsdt := 60000 * usdt.
+
+  self
+    assert: sixtyThousandUsdt / oneBitcoin * ( 10 * btc ) equals: 600000 * usdt;
+    assert:
+      sixtyThousandUsdt / oneBitcoin
+      * ( 10 * ( UnitOfAccount on: btc reference symbol: btc symbol ) )
+    equals: 600000 * usdt
+]
+
 { #category : 'tests' }
 UnitOfAccountTest >> testQuantitySubtraction [
 

source/Aconcagua-Quantitative-Analysis/DerivedDimension.class.st

@@ -28,7 +28,7 @@ DerivedDimension class >> composedOfAll: exponentsByDimension [
 { #category : 'private' }
 DerivedDimension class >> dictionaryClass [
 
-  ^ IdentityDictionary
+  ^ Dictionary
 ]
 
 { #category : 'instance creation' }