Error-Categories.adoc

Error-Lang Error Categories

Table of Contents

• 1. Overview
• 2. Error Category Taxonomy
  • 2.1. 1. Syntax Errors
  • 2.2. 2. Runtime Errors
  • 2.3. 3. Logical Errors
  • 2.4. 4. Semantic Errors
  • 2.5. 5. Linker Errors
  • 2.6. 6. Resource Errors
  • 2.7. 7. Arithmetic Errors
  • 2.8. 8. Interface Errors
  • 2.9. 9. Security Errors
• 3. Error Injection Strategy
  • 3.1. By Lesson Level
  • 3.2. Gutter Zone Rules
  • 3.3. Stability Score Impact
• 4. Implementation Notes
  • 4.1. Compiler Phases
  • 4.2. Error Message Format
• 5. Curriculum Integration

1. Overview

Error-Lang produces nine categories of errors as co-products of program development. Each category teaches different aspects of programming language theory and software engineering.

2. Error Category Taxonomy

2.1. 1. Syntax Errors

Phase: Lexical/Parsing

Errors in the structure of code that violate the language grammar.

Code	Error	Example
E0001	Unexpected token	let = 42
E0002	Unterminated string	"hello
E0003	Invalid escape	"\q"
E0004	Illegal character	let x = @
E0005	Missing 'end'	Unclosed block
E0006	Unmatched paren	(1 + 2
E0007	Smart quote	"hello" (curly)
E0008	Bad identifier	123abc
E0009	Reserved keyword	let if = 1
E0010	Whitespace issue	Bad indentation

Learning Objective: Understanding lexers and parsers

---

2.2. 2. Runtime Errors

Phase: Execution

Errors that occur during program execution.

Code	Error	Example
E0101	Null reference	nil.field
E0102	Index out of bounds	arr[999]
E0103	Stack overflow	Infinite recursion
E0104	Type mismatch	"a" + 1
E0105	Division by zero	1 / 0
E0106	Undefined variable	Using unbound name
E0107	Invalid operation	Operation not defined

Learning Objective: Understanding runtime behavior

---

2.3. 3. Logical Errors

Phase: Semantic Analysis

The program runs but produces incorrect results.

Code	Error	Example
E0201	Off-by-one	i < n vs i ⇐ n
E0202	Wrong operator	&& vs `
	`	E0203
Comparison inversion	a > b vs a < b	E0204
Assignment vs equality	= vs ==	E0205
Infinite loop	Missing increment	E0206
Dead code	Unreachable statements	E0207

Learning Objective: Debugging and testing

---

2.4. 4. Semantic Errors

Phase: Static Analysis

Code is syntactically valid but meaningless or contradictory.

Code	Error	Example
E0301	Type incompatibility	"str" + 42
E0302	Arity mismatch	fn(a,b) called with 1 arg
E0303	Duplicate definition	Same name twice
E0304	Shadowing warning	Inner scope hides outer
E0305	Unused variable	Declared but never used
E0306	Unreachable pattern	Match never taken
E0307	Invalid coercion	Types can’t convert

Learning Objective: Type systems and static analysis

---

2.5. 5. Linker Errors

Phase: Module Resolution

Errors in connecting program parts together.

Code	Error	Example
E0401	Module not found	import "missing"
E0402	Circular import	A imports B imports A
E0403	Symbol not exported	Using private symbol
E0404	Version mismatch	Incompatible module
E0405	Duplicate export	Same name exported twice
E0406	Missing dependency	Required module absent

Learning Objective: Module systems and dependencies

---

2.6. 6. Resource Errors

Phase: System Interaction

Errors related to system resources.

Code	Error	Example
E0501	File not found	open("missing.txt")
E0502	Permission denied	No read/write access
E0503	Out of memory	Too large allocation
E0504	Timeout	Operation too slow
E0505	Network error	Connection failed
E0506	Resource exhausted	Too many handles
E0507	Resource leak	Unclosed file/socket

Learning Objective: Resource management and cleanup

---

2.7. 7. Arithmetic Errors

Phase: Numeric Operations

Errors in mathematical computations.

Code	Error	Example
E0601	Division by zero	x / 0
E0602	Integer overflow	MAX_INT + 1
E0603	Underflow	MIN_INT - 1
E0604	NaN result	0.0 / 0.0
E0605	Infinity	1.0 / 0.0
E0606	Precision loss	Float rounding
E0607	Negative sqrt	sqrt(-1)

Learning Objective: Numeric representation and limits

---

2.8. 8. Interface Errors

Phase: API/Contract

Errors in interface contracts between components.

Code	Error	Example
E0701	Missing method	Interface not satisfied
E0702	Wrong signature	Method has wrong type
E0703	Precondition failed	Input validation
E0704	Postcondition failed	Output validation
E0705	Invariant violated	State corruption
E0706	Protocol violation	Wrong call order
E0707	Version incompatible	API changed

Learning Objective: Design by contract, APIs

---

2.9. 9. Security Errors

Phase: Safety Analysis

Errors that could lead to security vulnerabilities.

Code	Error	Example
E0801	Injection risk	Unescaped input
E0802	Buffer overflow	Writing past bounds
E0803	Path traversal	../../../etc/passwd
E0804	Sensitive data exposure	Logging secrets
E0805	Race condition	Concurrent access
E0806	Privilege escalation	Unauthorized action
E0807	Cryptographic weakness	Bad random, weak algo

Learning Objective: Secure coding practices

3. Error Injection Strategy

3.1. By Lesson Level

Level	Categories	Focus
Beginner	Syntax	Grammar and structure
Intermediate	Runtime, Logical	Debugging
Advanced	Semantic, Linker	Type systems, modules
Expert	Resource, Security	Systems programming

3.2. Gutter Zone Rules

The gutter (ошибка) block is where errors are injected:

1. One category per run - Each execution injects errors from one category

2. Progressive difficulty - Run counter affects category selection

3. Recoverable - All injected errors allow program continuation

4. Documented - Every error links to curriculum

3.3. Stability Score Impact

Category	Score Reduction	Reasoning
Syntax	-5	Common, easily fixed
Runtime	-10	More complex debugging
Logical	-15	Requires understanding intent
Semantic	-10	Type system concepts
Linker	-5	Configuration issues
Resource	-10	System interaction
Arithmetic	-10	Numeric edge cases
Interface	-15	Design concepts
Security	-20	Critical importance
Echo erasure	-15	Structured loss is not free: echo_to_residue debits stability ([Stab-Erase]), charged once and never on projection

Note	The Echo-erasure debit is not an error category — it is a deliberate, visible decomposition cost. It appears here because it feeds the same Stability Score. See docs/Echo-Decomposition.adoc and spec/type-system.md §7.

4. Implementation Notes

4.1. Compiler Phases

Source Code
    │
    ▼ [Syntax Errors: E00xx]
┌─────────┐
│  Lexer  │
└────┬────┘
     │
     ▼ [Syntax Errors: E00xx]
┌─────────┐
│ Parser  │
└────┬────┘
     │
     ▼ [Semantic Errors: E03xx]
┌─────────────┐
│ Type Check  │
└──────┬──────┘
       │
       ▼ [Linker Errors: E04xx]
┌─────────────┐
│ Module Res  │
└──────┬──────┘
       │
       ▼ [Runtime Errors: E01xx]
┌───────────┐  [Logical: E02xx]
│ Executor  │  [Resource: E05xx]
└─────┬─────┘  [Arithmetic: E06xx]
      │        [Interface: E07xx]
      ▼        [Security: E08xx]
   Output

4.2. Error Message Format

All errors follow this format:

Error-LangError: <file>:<line>:<col>: <message>
  [code=E#### category=<CAT> run=NNN]
  → Category: <Category Name>
  → Lesson: <Learning Objective>
  → Fix: <Recovery Strategy>

5. Curriculum Integration

Each error category maps to course modules:

1. Syntax → "Introduction to Parsing"

2. Runtime → "Program Execution"

3. Logical → "Debugging Techniques"

4. Semantic → "Type Systems"

5. Linker → "Module Systems"

6. Resource → "Systems Programming"

7. Arithmetic → "Numeric Computing"

8. Interface → "Software Design"

9. Security → "Secure Coding"