Learn Unlambda - 10 Code Examples & CST Typing Practice Test

Unlambda is an esoteric functional programming language based on combinatory logic. It eschews traditional variables and functions in favor of function application using only a small set of combinators, emphasizing minimalism and theoretical computation.

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Hello World in Unlambda Print Single Character Simple Function Application Repeat Printing Conditional Example Lambda Composition Nested Functions Looping Print Echo Input Character Complex Hello

Learn UNLAMBDA with Real Code Examples

Updated Nov 26, 2025

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Code Sample Descriptions

Hello World in Unlambda

`s``s`ks``s`k`s`kk
``s``s`ks``s`k`s`k``s`ksk
`k``s`k`s`k`k``s`ks``s`k`s`kk
.k
.e
.l
.l
.o
. 
.w
.o
.r
.l
.d
.!

A canonical 'Hello World' program in Unlambda. It uses backtick (`) for function application and .x to print characters.

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Print Single Character

.A

Prints a single character 'A' using Unlambda.

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Simple Function Application

`i.B

Demonstrates applying the identity function `i` to print 'B'.

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Repeat Printing

`k.C
C
C

Uses the `k` combinator to ignore an argument and print 'C' multiple times.

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Conditional Example

`s`k.Y
`k.N

Uses `s` and `k` combinators to simulate a simple conditional printing 'Y' or 'N'.

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Lambda Composition

`s`.A.B

Composes two functions to print 'AB'.

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Nested Functions

`s``s`ks``s`k`s`kk
.X
.Y

Demonstrates nested combinator applications to print 'XY'.

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Looping Print

`d`.Z
.Z
.Z

Uses recursion with `d` to print 'Z' three times.

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Echo Input Character

Reads a character from input and prints it.

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Complex Hello

`s``s`ks``s`k`s`kk
.k
.e
.l
.l
.o
.

Another 'Hello' example using nested combinators and `.x` printing.

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Frequently Asked Questions about Unlambda

What is Unlambda?

What are the primary use cases for Unlambda?

Experimenting with combinatory logic and functional programming. Educational examples in theoretical computer science. Recreational programming and code-golf challenges. Demonstrating Turing-completeness in minimal languages. Exploring minimalist programming paradigms

What are the strengths of Unlambda?

Demonstrates theoretical foundations of functional programming. Extremely small and minimal language. Challenges conventional programming paradigms. Good for educational and recreational purposes. Turing-complete and capable of arbitrary computation

What are the limitations of Unlambda?

Not practical for real-world programming. Difficult to read, write, and debug. Steep learning curve for beginners. Limited ecosystem and tooling. Mostly academic or hobbyist relevance

How can I practice Unlambda typing speed?

CodeSpeedTest offers 10+ real Unlambda code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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Learn Unlambda - 10 Code Examples & CST Typing Practice Test

Code Sample Descriptions

Hello World in Unlambda

`s``s`ks``s`k`s`kk
``s``s`ks``s`k`s`k``s`ksk
`k``s`k`s`k`k``s`ks``s`k`s`kk
.k
.e
.l
.l
.o
. 
.w
.o
.r
.l
.d
.!

A canonical 'Hello World' program in Unlambda. It uses backtick (`) for function application and .x to print characters.

Let’s Try →

Print Single Character

.A

Prints a single character 'A' using Unlambda.

Let’s Try →

Simple Function Application

`i.B

Demonstrates applying the identity function `i` to print 'B'.

Let’s Try →

Repeat Printing

`k.C
C
C

Uses the `k` combinator to ignore an argument and print 'C' multiple times.

Let’s Try →

Conditional Example

`s`k.Y
`k.N

Uses `s` and `k` combinators to simulate a simple conditional printing 'Y' or 'N'.

Let’s Try →

Lambda Composition

`s`.A.B

Composes two functions to print 'AB'.

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Nested Functions

`s``s`ks``s`k`s`kk
.X
.Y

Demonstrates nested combinator applications to print 'XY'.

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Looping Print

`d`.Z
.Z
.Z

Uses recursion with `d` to print 'Z' three times.

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Echo Input Character

Reads a character from input and prints it.

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Complex Hello

`s``s`ks``s`k`s`kk
.k
.e
.l
.l
.o
.

Another 'Hello' example using nested combinators and `.x` printing.

Let’s Try →

Frequently Asked Questions about Unlambda

What is Unlambda?

What are the primary use cases for Unlambda?

What are the strengths of Unlambda?

What are the limitations of Unlambda?

Not practical for real-world programming. Difficult to read, write, and debug. Steep learning curve for beginners. Limited ecosystem and tooling. Mostly academic or hobbyist relevance

How can I practice Unlambda typing speed?

CodeSpeedTest offers 10+ real Unlambda code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.