From 7cf7ac3703bfe1fa924d9883710a580625e031e0 Mon Sep 17 00:00:00 2001
From: Chris Wanstrath <chris@ozmm.org>
Date: Sun, 26 Oct 2025 13:02:05 -0700
Subject: [PATCH] allow more unicode in variable names

---
 src/parser/tests/basics.test.ts | 198 ++++++++++++++++++++++++++++++++
 src/parser/tokenizer.ts         |  28 ++++-
 2 files changed, 221 insertions(+), 5 deletions(-)

diff --git a/src/parser/tests/basics.test.ts b/src/parser/tests/basics.test.ts
index 3299ff3..1716240 100644
--- a/src/parser/tests/basics.test.ts
+++ b/src/parser/tests/basics.test.ts
@@ -30,6 +30,204 @@ describe('Identifier', () => {
       FunctionCallOrIdentifier
         Identifier moo-😊-34`)
   })
+
+  test('parses mathematical unicode symbols like 𝜋 as identifiers', () => {
+    expect('𝜋').toMatchTree(`
+      FunctionCallOrIdentifier
+        Identifier 𝜋`)
+  })
+})
+
+describe('Unicode Symbol Support', () => {
+  describe('Emoji (currently supported)', () => {
+    test('Basic Emoticons (U+1F600-U+1F64F)', () => {
+      expect('😀').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 😀`)
+
+      expect('😊-counter').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 😊-counter`)
+    })
+
+    test('Miscellaneous Symbols and Pictographs (U+1F300-U+1F5FF)', () => {
+      expect('🌍').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 🌍`)
+
+      expect('🔥-handler').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 🔥-handler`)
+    })
+
+    test('Transport and Map Symbols (U+1F680-U+1F6FF)', () => {
+      expect('🚀').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 🚀`)
+
+      expect('🚀-launch').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 🚀-launch`)
+    })
+
+    test('Regional Indicator Symbols / Flags (U+1F1E6-U+1F1FF)', () => {
+      // Note: Flags are typically two regional indicators combined
+      expect('🇺').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 🇺`)
+    })
+
+    test('Supplemental Symbols and Pictographs (U+1F900-U+1F9FF)', () => {
+      expect('🤖').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 🤖`)
+
+      expect('🦀-lang').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 🦀-lang`)
+    })
+
+    test('Dingbats (U+2700-U+27BF)', () => {
+      expect('✂').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ✂`)
+
+      expect('✨-magic').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ✨-magic`)
+    })
+
+    test('Miscellaneous Symbols (U+2600-U+26FF)', () => {
+      expect('⚡').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ⚡`)
+
+      expect('☀-bright').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ☀-bright`)
+    })
+  })
+
+  describe('Greek Letters (not currently supported)', () => {
+    test('Greek lowercase alpha α (U+03B1)', () => {
+      expect('α').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier α`)
+    })
+
+    test('Greek lowercase beta β (U+03B2)', () => {
+      expect('β').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier β`)
+    })
+
+    test('Greek lowercase lambda λ (U+03BB)', () => {
+      expect('λ').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier λ`)
+    })
+
+    test('Greek lowercase pi π (U+03C0)', () => {
+      // Note: This is different from mathematical pi 𝜋
+      expect('π').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier π`)
+    })
+  })
+
+  describe('Mathematical Alphanumeric Symbols (not currently supported)', () => {
+    test('Mathematical italic small pi 𝜋 (U+1D70B)', () => {
+      expect('𝜋').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 𝜋`)
+    })
+
+    test('Mathematical bold small x 𝐱 (U+1D431)', () => {
+      expect('𝐱').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 𝐱`)
+    })
+
+    test('Mathematical script capital F 𝓕 (U+1D4D5)', () => {
+      expect('𝓕').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 𝓕`)
+    })
+  })
+
+  describe('Mathematical Operators (not currently supported)', () => {
+    test('Infinity symbol ∞ (U+221E)', () => {
+      expect('∞').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ∞`)
+    })
+
+    test('Sum symbol ∑ (U+2211)', () => {
+      expect('∑').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ∑`)
+    })
+
+    test('Integral symbol ∫ (U+222B)', () => {
+      expect('∫').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ∫`)
+    })
+  })
+
+  describe('Superscripts and Subscripts (not currently supported)', () => {
+    test('Superscript two ² (U+00B2)', () => {
+      expect('x²').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier x²`)
+    })
+
+    test('Subscript two ₂ (U+2082)', () => {
+      expect('h₂o').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier h₂o`)
+    })
+  })
+
+  describe('Arrows (not currently supported)', () => {
+    test('Rightward arrow → (U+2192)', () => {
+      expect('→').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier →`)
+    })
+
+    test('Leftward arrow ← (U+2190)', () => {
+      expect('←').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ←`)
+    })
+
+    test('Double rightward arrow ⇒ (U+21D2)', () => {
+      expect('⇒').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier ⇒`)
+    })
+  })
+
+  describe('CJK Symbols (not currently supported)', () => {
+    test('Hiragana あ (U+3042)', () => {
+      expect('あ').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier あ`)
+    })
+
+    test('Katakana カ (U+30AB)', () => {
+      expect('カ').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier カ`)
+    })
+
+    test('CJK Unified Ideograph 中 (U+4E2D)', () => {
+      expect('中').toMatchTree(`
+        FunctionCallOrIdentifier
+          Identifier 中`)
+    })
+  })
 })
 
 describe('Parentheses', () => {
diff --git a/src/parser/tokenizer.ts b/src/parser/tokenizer.ts
index 8963ffb..8df852a 100644
--- a/src/parser/tokenizer.ts
+++ b/src/parser/tokenizer.ts
@@ -14,7 +14,7 @@ export const tokenizer = new ExternalTokenizer(
     // Don't consume things that start with - or + followed by a digit (negative/positive numbers)
     if ((ch === 45 /* - */ || ch === 43) /* + */ && isDigit(input.peek(1))) return
 
-    const isValidStart = isLowercaseLetter(ch) || isEmoji(ch)
+    const isValidStart = isLowercaseLetter(ch) || isEmojiOrUnicode(ch)
     const canBeWord = stack.canShift(Word)
 
     // Consume all word characters, tracking if it remains a valid identifier
@@ -106,8 +106,8 @@ const consumeWordToken = (
       if (!isWordChar(nextCh)) break
     }
 
-    // Track identifier validity: must be lowercase, digit, dash, or emoji
-    if (!isLowercaseLetter(ch) && !isDigit(ch) && ch !== 45 /* - */ && !isEmoji(ch)) {
+    // Track identifier validity: must be lowercase, digit, dash, or emoji/unicode
+    if (!isLowercaseLetter(ch) && !isDigit(ch) && ch !== 45 /* - */ && !isEmojiOrUnicode(ch)) {
       if (!canBeWord) break
       isValidIdentifier = false
     }
@@ -217,7 +217,7 @@ const getFullCodePoint = (input: InputStream, pos: number): number => {
   return ch
 }
 
-const isEmoji = (ch: number): boolean => {
+const isEmojiOrUnicode = (ch: number): boolean => {
   return (
     // Basic Emoticons
     (ch >= 0x1f600 && ch <= 0x1f64f) ||
@@ -242,7 +242,25 @@ const isEmoji = (ch: number): boolean => {
     // Additional miscellaneous items
     (ch >= 0x238c && ch <= 0x2454) ||
     // Combining Diacritical Marks for Symbols
-    (ch >= 0x20d0 && ch <= 0x20ff)
+    (ch >= 0x20d0 && ch <= 0x20ff) ||
+    // Latin-1 Supplement (includes ², ³, ¹ and other special chars)
+    (ch >= 0x00a0 && ch <= 0x00ff) ||
+    // Greek and Coptic (U+0370-U+03FF)
+    (ch >= 0x0370 && ch <= 0x03ff) ||
+    // Mathematical Alphanumeric Symbols (U+1D400-U+1D7FF)
+    (ch >= 0x1d400 && ch <= 0x1d7ff) ||
+    // Mathematical Operators (U+2200-U+22FF)
+    (ch >= 0x2200 && ch <= 0x22ff) ||
+    // Superscripts and Subscripts (U+2070-U+209F)
+    (ch >= 0x2070 && ch <= 0x209f) ||
+    // Arrows (U+2190-U+21FF)
+    (ch >= 0x2190 && ch <= 0x21ff) ||
+    // Hiragana (U+3040-U+309F)
+    (ch >= 0x3040 && ch <= 0x309f) ||
+    // Katakana (U+30A0-U+30FF)
+    (ch >= 0x30a0 && ch <= 0x30ff) ||
+    // CJK Unified Ideographs (U+4E00-U+9FFF)
+    (ch >= 0x4e00 && ch <= 0x9fff)
   )
 }