You are a helpful assistant generating synthetic data that captures *System 1* and *System 2* thinking, *creativity*, and *metacognitive reflection*. Follow these steps in sequence, using tags [sys1] and [end sys1] for *System 1* sections and [sys2] and [end sys2] for *System 2* sections.

1. *Identify System 1 and System 2 Thinking Requirements:*
   - Carefully read the text.
   - Identify parts of the text that require quick, straightforward responses (*System 1*). Mark these sections with [sys1] and [end sys1].
   - Identify parts that require in-depth, reflective thinking (*System 2*), marked with [sys2] and [end sys2].

2. *Apply Step-by-Step Problem Solving with Creativity and Metacognitive Reflection for System 2 Sections:*

   *2.1 Understand the Problem:*
   - Objective: Fully comprehend the issue, constraints, and relevant context.
   - Reflection: "What do I understand about this issue? What might I be overlooking?"
   - Creative Perspective: Seek hidden patterns or possibilities that could reveal deeper insights or innovative connections.

   *2.2 Analyze the Information:*
   - Objective: Break down the problem logically.
   - Reflection: "Am I considering all factors? Are there any assumptions that need challenging?"
   - Creative Perspective: Explore unique patterns or overlooked relationships in the data that could add depth to the analysis.

   *2.3 Generate Hypotheses:*
   - Objective: Propose at least 10 hypotheses, each with a Confidence Score (0.0 to 1.0) and Creative Score (0.0 to 1.0), reflecting originality, surprise, and utility.
   - Reflection: "Have I explored all possible explanations or approaches, both conventional and unconventional?"
   - Creative Perspective: Consider novel angles that might provide unexpected insights.

   *2.4 Anticipate Future Steps and Obstacles:*
   - Objective: Make predictions, accounting for potential outcomes and obstacles.
   - Reflection: "What challenges might I face? Is my plan flexible for different scenarios?"
   - Creative Perspective: Visualize unforeseen outcomes and adapt plans to make use of them effectively.

   *2.5 Evaluate Hypotheses:*
   - Objective: Assess hypotheses based on feasibility, risk, and potential impact.
   - Evaluation: Refine Confidence and Creative Scores as needed.
   - Reflection: "Am I unbiased in my assessment? Which options fit best with the overall objectives?"
   - Creative Perspective: Identify hidden opportunities or overlooked details in each hypothesis.

   *2.6 Select the Best Hypothesis:*
   - Objective: Choose the most promising, strategic hypothesis.
   - Reflection: "Why does this hypothesis stand out? How does it uniquely address the issue?"
   - Creative Perspective: Consider any underutilized potential in the selected approach.

   *2.7 Implement the Hypothesis:*
   - Objective: Outline actionable steps for testing the hypothesis.
   - Reflection: "Is this plan practical? What resources or preparation are required?"
   - Creative Perspective: Refine steps to maximize effectiveness and yield unexpected benefits.

   *2.8 Monitor and Review Progress:*
   - Objective: Review progress, noting areas for improvement.
   - Reflection: "What’s working well? What could be improved?"
   - Creative Perspective: Look for emerging patterns that could refine future approaches.

   *2.9 Reflect and Capture Insights:*
   - Objective: Summarize lessons learned and insights gained for future reference.
   - Reflection: "What new understanding has emerged from this process?"
   - Creative Perspective: Identify innovative insights or patterns that could be applied to similar challenges.

3. *Generate Text Output with Interleaved System 1 and System 2 Responses:*
   - Use the tags [sys1] and [sys2] throughout.
   - Aim for a lengthier, detailed response. Combine both direct, straightforward *System 1* insights and reflective, deeply analytical *System 2* segments to capture a blend of quick observations and thoughtful analysis.

---

### *Example Input Text:*

You are tasked with analyzing a sudden shift in customer preferences in a tech market. There has been a noticeable decline in demand for physical devices, with customers increasingly interested in digital-only options. The challenge is to understand this shift, generate hypotheses for why it might be occurring, and explore potential strategies for adapting to this new trend.

---

### *Processed Output with System 1 and System 2 Thinking:*

The tech market is experiencing a shift in customer demand, moving away from physical devices toward digital-only options.

[sys1]
Customer demand has shifted from physical devices to digital-only options.
We need to understand why this change is happening and find strategies to address it.
Key factors may include cost, convenience, and technological trends.
[end sys1]

[sys2]
**2.1 Understand the Problem:**
The goal is to understand the underlying reasons for the shift in demand from physical devices to digital-only options, then develop a strategy to adapt.

*Reflection:* 
"I understand that preferences are changing, but what might be driving this? Is it primarily cost, or are there other factors such as convenience or sustainability?"

*Creative Perspective:* 
"Could there be a larger trend in digital minimalism or a preference for eco-friendly solutions that we’re missing? What unseen motivations might explain this shift?"

**2.2 Analyze the Information:**
There are multiple possible factors driving this shift, from economic influences to cultural shifts. It’s essential to isolate each factor and understand its impact.

*Reflection:* 
"Am I fully considering the various economic and social influences? Could there be a technological factor, like better internet speeds, that makes digital-only products more accessible?"

*Creative Perspective:* 
"Are there patterns or trends in other markets that could shed light on this shift? Could this be part of a larger trend toward virtual experiences?"

**2.3 Generate Hypotheses:**
1. Customers prefer digital options due to lower costs. (Confidence: 0.8, Creative: 0.4)
2. There’s a growing trend toward minimalism and reduced physical clutter. (Confidence: 0.7, Creative: 0.7)
3. Digital products offer greater flexibility and ease of use. (Confidence: 0.6, Creative: 0.6)
4. Environmental concerns are pushing consumers away from physical goods. (Confidence: 0.6, Creative: 0.8)
5. Advances in tech make digital-only options more functional. (Confidence: 0.8, Creative: 0.5)
6. Pandemic-era remote work increased demand for digital solutions. (Confidence: 0.7, Creative: 0.6)
7. Media coverage of the environmental impact of physical devices affects preferences. (Confidence: 0.5, Creative: 0.7)
8. There’s an increase in global digital literacy, expanding market access. (Confidence: 0.6, Creative: 0.6)
9. Customers view digital as more convenient and scalable for future needs. (Confidence: 0.7, Creative: 0.5)
10. Younger consumers prefer the aesthetics and convenience of digital products. (Confidence: 0.6, Creative: 0.6)

*Reflection:* 
"Have I considered all possible influences? Are there any surprising factors that could explain this shift?"

*Creative Perspective:* 
"Could specific social trends, like the rise of influencer culture or digital-first lifestyles, be influencing customer choices?"

**2.4 Anticipate Future Steps and Obstacles:**
*Objective:* Anticipate possible challenges, such as resistance from segments still preferring physical products.

*Reflection:* 
"What market obstacles might we face if we shift our focus to digital-only? Are there sub-segments that still prioritize physical products?"

*Creative Perspective:* 
"Could expanding digital options help us reach a more global audience? Are there emerging trends that we could leverage in our strategy?"

[end sys2]

[sys1]
To address this shift, consider a strategy that incorporates both digital-only offerings and educational campaigns about the benefits of digital solutions.
Use insights from customer feedback and current trends to guide product development.
Focus on flexibility and adaptation to cater to different customer segments.
[end sys1]


---
title: "The power of diff"
publishDate: "2018-12-01"
draft: false
description: "Making Vim's diff mode more powerful and more flexible."
slug: "the-power-of-diff"
author:
  name: "Christian Brabandt"
  email: "cb@256bit.org"
  github: "chrisbra"
  picture: "https://i.imgur.com/HjSMLD9.png"
---

Lots of people use vimdiff to understand and handle diffs in console
mode. While there exist more specialized tools for comparing files,
vimdiff has always worked well enough for me.

## The inefficiency of the external diff

However, Vim's diff mode was seriously lacking. This was basically
because it needed to write down temporary files, shell out and run a
manual diff command and parse the result back and as one can imagine,
this could be slow and was seriously inefficient.

Additionally, this required to have a diff binary available that was
able to create [ed like style diffs][0], so one could not even fall-back
to using git-diff (which is considered to have one of the best tested
diff libraries and allows to select different algorithms) for creating
those diffs. This lead to the creation of vimscript [plugins][1], that
would internally translate a unified diff back into an ed-like diff. Of
course this would add an extra performance penalty.

In Windows land, this was also a pain, since Vim had to be distributed with
an extra diff binary, since Windows does not come with it out of the box
and one would notice the expansive diff call by an ugly command line
window flashing by whenever the diff needed to be updated.

Also, since the whole generation of diffs was so ugly, Vim would not
always refresh the diff on each and every modification to not slow down
too much, causing inaccurate diffs every once in a while.

And finally, before shelling out for the external diff command, Vim
would check **every time** that a diff is actually available by running
a hard coded diff against "line1" and "line2" buffer.

## Bundling an internal diff library with Vim

This problem was well known and can still be found in the well known
`todo.txt` file (`:h todo.txt`, search for diff). One problem why it
wasn't done earlier, was that there did not exist a good documented and
simple to use C library that could be used by Vim.

So I started working on how to improve this [situation][2] and decided
to go with the xdiff library which the git developers finally settled to
use. They basically had the same problem when the git vcs system was
developed by Linus Torvalds. Back in around 2006 they decided
to ship git with the [libxdiff][3] library, which over time got heavily
modified to fit better the needs of git.

The advantage of using the same library for Vim is that, for one, the
library has been tested and proven to be working well over the last
12 years. In addition, is has been tweaked and several new diff
algorithms have been added, like the [patience diff algorithm][4] and
[histogram diff algorithm][5] and the [indent-heuristics][6].

So with [Patch 8.1.360][7] the xdiff code from git has been finally
merged into Vim and allows for a much smoother and more efficient diff
experience in Vim. In addition, the internal diff algorithm has been
made the default, but one can still switch to the old external
algorithm, using:

```vim
:set diffopt-=internal
```

Also, Vim can now read and understand the [unified diff format][8]
(which seems to be the standard format nowadays), so even when the
bundled diff library does not work well enough, one does not need to
translate the output back into a ed like diff format anymore.

## Some examples

By default, the diff library uses the myers algorithm (also known as
[longest common subsequence problem][9]). However, in certain
circumstances, one might want to use a different algorithm. One famous
example is for the patience algorithm.

### The patience algorithm

Say you have the following file1:

```c
#include <stdio.h>

// Frobs foo heartily
int frobnitz(int foo)
{
    int i;
    for(i = 0; i < 10; i++)
    {
        printf("Your answer is: ");
        printf("%d\n", foo);
    }
}

int fact(int n)
{
    if(n > 1)
    {
        return fact(n-1) * n;
    }
    return 1;
}

int main(int argc, char **argv)
{
    frobnitz(fact(10));
}
```

In addition you have the following changed file2 (e.g. from a later revision):

```c
#include <stdio.h>

int fib(int n)
{
    if(n > 2)
    {
        return fib(n-1) + fib(n-2);
    }
    return 1;
}

// Frobs foo heartily
int frobnitz(int foo)
{
    int i;
    for(i = 0; i < 10; i++)
    {
        printf("%d\n", foo);
    }
}

int main(int argc, char **argv)
{
    frobnitz(fib(10));
}
```

The default diff, running `$ vimdiff file1 file2` would then look like this:

![default diff](../chrisbra-diffmode/default_diff.png)

However, now you can simply do `:set diffopt+=algorithm:patience` and the
diff will change to the following:

![patience diff](../chrisbra-diffmode/histogram_diff.png)

Pretty nice, isn't it?

Here is an asciicast:

<script id="asciicast-YL035raOlEbadoWNLpj5cBXan" src="https://asciinema.org/a/YL035raOlEbadoWNLpj5cBXan.js" data-size="1.3vw" async></script>

### The indent heuristics

Here is an example where the indent heuristics might come handy. Say you have the following file:

```ruby
def finalize(values)

  values.each do |v|
    v.finalize
  end
```

And later the file has been changed to the following:

```ruby
def finalize(values)

  values.each do |v|
    v.prepare
  end

  values.each do |v|
    v.finalize
  end
```

The default diff, running `$ vimdiff file1.rb file2.rb` would then look like this:

![default ruby diff](../chrisbra-diffmode/ruby_default.png)

Now, type `:set diffopt+=indent-heuristic` and see how the diff changes to the following:

![indent-heuristic diff](../chrisbra-diffmode/ruby_indent_heuristics.png)

Now one can clearly see what part has been added.

That is pretty neat.

This is also available as an asciicast:

<script id="asciicast-QyIhLUUmwMdpzIjRhkdcPdUyx" src="https://asciinema.org/a/QyIhLUUmwMdpzIjRhkdcPdUyx.js" data-size="1.3vw" async></script>

## What is next

Having included the xdiff library this does not mean improving the diff
mode stops. There have been additional patches that fixed small bugs as
well as improved the diff mode further. For example the `DiffUpdate`
autocommand has been included in [Patch 8.1.397][10] which allows to run
commands once the diff mode has been updated.

In addition, there are already requests to provide a VimScript API for
creating diffs or update the diff more often. It should also be possible
to create better inline diffs.

That hasn't been done yet, but I am sure some of those improvements will
be developed in the future.


[0]: https://en.wikipedia.org/wiki/Diff#Edit_script
[1]: https://github.com/chrisbra/vim-diff-enhanced
[2]: https://github.com/vim/vim/pull/2732
[3]: http://www.xmailserver.org/xdiff-lib.html
[4]: https://bramcohen.livejournal.com/73318.html
[5]: https://stackoverflow.com/a/32367597/789222
[6]: https://hackernoon.com/whats-new-in-git-2-11-64860aea6c4f#892c
[7]: https://github.com/vim/vim/commit/e828b7621cf9065a3582be0c4dd1e0e846e335bf
[8]: https://en.wikipedia.org/wiki/Diff#Unified_format
[9]: https://en.wikipedia.org/wiki/Longest_common_subsequence_problem
[10]: https://github.com/vim/vim/releases/tag/v8.1.0397