code-simplification

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• Code is already clean and readable — don't simplify for the sake of it

• You don't understand what the code does yet — comprehend before you simplify

• The code is performance-critical and the "simpler" version would be measurably slower

• You're about to rewrite the module entirely — simplifying throwaway code wastes effort

The Five Principles

1. Preserve Behavior Exactly

Don't change what the code does — only how it expresses it. All inputs, outputs, side effects, error behavior, and edge cases must remain identical. If you're not sure a simplification preserves behavior, don't make it.

ASK BEFORE EVERY CHANGE:

→ Does this produce the same output for every input?

→ Does this maintain the same error behavior?

→ Does this preserve the same side effects and ordering?

→ Do all existing tests still pass without modification?

2. Follow Project Conventions

Simplification means making code more consistent with the codebase, not imposing external preferences. Before simplifying:

1. Read CLAUDE.md / project conventions

2. Study how neighboring code handles similar patterns

3. Match the project's style for:

   - Import ordering and module system

   - Function declaration style

   - Naming conventions

   - Error handling patterns

   - Type annotation depth

Simplification that breaks project consistency is not simplification — it's churn.

3. Prefer Clarity Over Cleverness

Explicit code is better than compact code when the compact version requires a mental pause to parse.

// UNCLEAR: Dense ternary chain

const label = isNew ? 'New' : isUpdated ? 'Updated' : isArchived ? 'Archived' : 'Active';

// CLEAR: Readable mapping

function getStatusLabel(item: Item): string {

  if (item.isNew) return 'New';

  if (item.isUpdated) return 'Updated';

  if (item.isArchived) return 'Archived';

  return 'Active';

}

// UNCLEAR: Chained reduces with inline logic

const result = items.reduce((acc, item) => ({

  ...acc,

  [item.id]: { ...acc[item.id], count: (acc[item.id]?.count ?? 0) + 1 }

}), {});

// CLEAR: Named intermediate step

const countById = new Map<string, number>();

for (const item of items) {

  countById.set(item.id, (countById.get(item.id) ?? 0) + 1);

}

4. Maintain Balance

Simplification has a failure mode: over-simplification. Watch for these traps:

• Inlining too aggressively — removing a helper that gave a concept a name makes the call site harder to read

• Combining unrelated logic — two simple functions merged into one complex function is not simpler

• Removing "unnecessary" abstraction — some abstractions exist for extensibility or testability, not complexity

• Optimizing for line count — fewer lines is not the goal; easier comprehension is

5. Scope to What Changed

Default to simplifying recently modified code. Avoid drive-by refactors of unrelated code unless explicitly asked to broaden scope. Unscoped simplification creates noise in diffs and risks unintended regressions.

The Simplification Process

Step 1: Understand Before Touching (Chesterton's Fence)

Before changing or removing anything, understand why it exists. This is Chesterton's Fence: if you see a fence across a road and don't understand why it's there, don't tear it down. First understand the reason, then decide if the reason still applies.

BEFORE SIMPLIFYING, ANSWER:

- What is this code's responsibility?

- What calls it? What does it call?

- What are the edge cases and error paths?

- Are there tests that define the expected behavior?

- Why might it have been written this way? (Performance? Platform constraint? Historical reason?)

- Check git blame: what was the original context for this code?

If you can't answer these, you're not ready to simplify. Read more context first.

Step 2: Identify Simplification Opportunities

Scan for these patterns — each one is a concrete signal, not a vague smell:

Structural complexity:

Pattern

Signal

Simplification

Deep nesting (3+ levels)

Hard to follow control flow

Extract conditions into guard clauses or helper functions

Long functions (50+ lines)

Multiple responsibilities

Split into focused functions with descriptive names

Nested ternaries

Requires mental stack to parse

Replace with if/else chains, switch, or lookup objects

Boolean parameter flags

doThing(true, false, true)

Replace with options objects or separate functions

Repeated conditionals

Same if check in multiple places

Extract to a well-named predicate function

Naming and readability:

Pattern

Signal

Simplification

Generic names

data, result, temp, val, item

Rename to describe the content: userProfile, validationErrors

Abbreviated names

usr, cfg, btn, evt

Use full words unless the abbreviation is universal (id, url, api)

Misleading names

Function named get that also mutates state

Rename to reflect actual behavior

Comments explaining "what"

// increment counter above count++

Delete the comment — the code is clear enough

Comments explaining "why"

// Retry because the API is flaky under load

Keep these — they carry intent the code can't express

Redundancy:

Pattern

Signal

Simplification

Duplicated logic

Same 5+ lines in multiple places

Extract to a shared function

Dead code

Unreachable branches, unused variables, commented-out blocks

Remove (after confirming it's truly dead)

Unnecessary abstractions

Wrapper that adds no value

Inline the wrapper, call the underlying function directly

Over-engineered patterns

Factory-for-a-factory, strategy-with-one-strategy

Replace with the simple direct approach

Redundant type assertions

Casting to a type that's already inferred

Remove the assertion

Step 3: Apply Changes Incrementally

Make one simplification at a time. Run tests after each change. Submit refactoring changes separately from feature or bug fix changes. A PR that refactors and adds a feature is two PRs — split them.

FOR EACH SIMPLIFICATION:

1. Make the change

2. Run the test suite

3. If tests pass → commit (or continue to next simplification)

4. If tests fail → revert and reconsider

Avoid batching multiple simplifications into a single untested change. If something breaks, you need to know which simplification caused it.

The Rule of 500: If a refactoring would touch more than 500 lines, invest in automation (codemods, sed scripts, AST transforms) rather than making the changes by hand. Manual edits at that scale are error-prone and exhausting to review.

Step 4: Verify the Result

After all simplifications, step back and evaluate the whole:

COMPARE BEFORE AND AFTER:

- Is the simplified version genuinely easier to understand?

- Did you introduce any new patterns inconsistent with the codebase?

- Is the diff clean and reviewable?

- Would a teammate approve this change?

If the "simplified" version is harder to understand or review, revert. Not every simplification attempt succeeds.

Language-Specific Guidance

TypeScript / JavaScript

// SIMPLIFY: Unnecessary async wrapper

// Before

async function getUser(id: string): Promise<User> {

  return await userService.findById(id);

}

// After

function getUser(id: string): Promise<User> {

  return userService.findById(id);

}

// SIMPLIFY: Verbose conditional assignment

// Before

let displayName: string;

if (user.nickname) {

  displayName = user.nickname;

} else {

  displayName = user.fullName;

}

// After

const displayName = user.nickname || user.fullName;

// SIMPLIFY: Manual array building

// Before

const activeUsers: User[] = [];

for (const user of users) {

  if (user.isActive) {

    activeUsers.push(user);

  }

}

// After

const activeUsers = users.filter((user) => user.isActive);

// SIMPLIFY: Redundant boolean return

// Before

function isValid(input: string): boolean {

  if (input.length > 0 &#x26;&#x26; input.length < 100) {

    return true;

  }

  return false;

}

// After

function isValid(input: string): boolean {

  return input.length > 0 &#x26;&#x26; input.length < 100;

}

Python

# SIMPLIFY: Verbose dictionary building

# Before

result = {}

for item in items:

    result[item.id] = item.name

# After

result = {item.id: item.name for item in items}

# SIMPLIFY: Nested conditionals with early return

# Before

def process(data):

    if data is not None:

        if data.is_valid():

            if data.has_permission():

                return do_work(data)

            else:

                raise PermissionError("No permission")

        else:

            raise ValueError("Invalid data")

    else:

        raise TypeError("Data is None")

# After

def process(data):

    if data is None:

        raise TypeError("Data is None")

    if not data.is_valid():

        raise ValueError("Invalid data")

    if not data.has_permission():

        raise PermissionError("No permission")

    return do_work(data)

React / JSX

// SIMPLIFY: Verbose conditional rendering

// Before

function UserBadge({ user }: Props) {

  if (user.isAdmin) {

    return <Badge variant="admin">Admin</Badge>;

  } else {

    return <Badge variant="default">User</Badge>;

  }

}

// After

function UserBadge({ user }: Props) {

  const variant = user.isAdmin ? 'admin' : 'default';

  const label = user.isAdmin ? 'Admin' : 'User';

  return <Badge variant={variant}>{label}</Badge>;

}

// SIMPLIFY: Prop drilling through intermediate components

// Before — consider whether context or composition solves this better.

// This is a judgment call — flag it, don't auto-refactor.

Common Rationalizations

Rationalization

Reality

"It's working, no need to touch it"

Working code that's hard to read will be hard to fix when it breaks. Simplifying now saves time on every future change.

"Fewer lines is always simpler"

A 1-line nested ternary is not simpler than a 5-line if/else. Simplicity is about comprehension speed, not line count.

"I'll just quickly simplify this unrelated code too"

Unscoped simplification creates noisy diffs and risks regressions in code you didn't intend to change. Stay focused.

"The types make it self-documenting"

Types document structure, not intent. A well-named function explains why better than a type signature explains what.

"This abstraction might be useful later"

Don't preserve speculative abstractions. If it's not used now, it's complexity without value. Remove it and re-add when needed.

"The original author must have had a reason"

Maybe. Check git blame — apply Chesterton's Fence. But accumulated complexity often has no reason; it's just the residue of iteration under pressure.

"I'll refactor while adding this feature"

Separate refactoring from feature work. Mixed changes are harder to review, revert, and understand in history.

Red Flags

• Simplification that requires modifying tests to pass (you likely changed behavior)

• "Simplified" code that is longer and harder to follow than the original

• Renaming things to match your preferences rather than project conventions

• Removing error handling because "it makes the code cleaner"

• Simplifying code you don't fully understand

• Batching many simplifications into one large, hard-to-review commit

• Refactoring code outside the scope of the current task without being asked

Verification

After completing a simplification pass:

• All existing tests pass without modification

• Build succeeds with no new warnings

• Linter/formatter passes (no style regressions)

• Each simplification is a reviewable, incremental change

• The diff is clean — no unrelated changes mixed in

• Simplified code follows project conventions (checked against CLAUDE.md or equivalent)

• No error handling was removed or weakened

• No dead code was left behind (unused imports, unreachable branches)

• A teammate or review agent would approve the change as a net improvement