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Akira Shimodate
Akira Shimodate

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Are User-Defined Literals Necessary in C#?

#csharp #dotnet #programming #languagedesign

A Step Toward Meaningful Values

Conclusion

This is not a new idea.

👉 It is a continuation of how C# has been evolving.

Giving meaning directly to values is a natural evolution of C#.

C# has been moving in this direction for years.

This article proposes User-Defined Literals (UDL) as a natural
continuation of that evolution.

The Current Limitation 

var duration = 123;
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We don't know:

  • seconds?\
  • milliseconds?

No meaning.

Current Solution 

123.Milliseconds()
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Meaning depends on API.

The Core Problem

Traditionally, meaning is attached after the value is created.

UDL shifts that boundary.

Values themselves have no meaning.

Proposal 

var duration = 123_ms;
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Now:

  • Type is known\
  • Meaning is known

Meaning is embedded in the value.

Why This Is Natural

C# has already evolved:

  • foreach (pattern-based)\
  • await (pattern-based)\
  • using (pattern-based)

Language privileges have been opened.

See also:\
👉 (https://dev.to/shimodateakira/why-c-keeps-opening-its-syntax-and-why-it-matters-3l7f)

Common Misconception

Literal = compile-time constant

Not true.

var s = $"{DateTime.Now}";
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Literal is syntax, not evaluation timing.

Summary

  • APIs attach meaning later\
  • Literals carry meaning immediately

This is not syntax sugar. It's a design shift.

Final Thought

So the real question is:

Should values themselves carry meaning?

And if so:

How far should C# go in that direction?

I'm curious how others see this.

Is this a natural evolution of C#,
or are we just moving complexity from APIs into the language itself?

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