<p><a href="http://en.wikipedia.org/wiki/Jensen%27s_Device" rel="nofollow noreferrer">Jensen's device</a> was developed by <a href="http://en.wikipedia.org/wiki/J%C3%B8rn_Jensen" rel="nofollow noreferrer">Jørn Jensen</a>, who worked on one of the earliest ALGOL 60 compilers (this answer is based on <a href="https://cstheory.stackexchange.com/questions/16158/lambda-the-ultimate-imperative-who-is-jensen#comment41960_16158">comment by Kristoffer Arnsfelt Hansen</a>).</p>

CC BY-SA 3.0
2013-01-21T12:26:32.140Z
2013-01-21T12:26:32.140Z
2017-04-13T12:32:28.080Z
Jan Stolarek
<p>One of the notes in the classical paper <a href="http://repository.readscheme.org/ftp/papers/ai-lab-pubs/AIM-353.pdf" rel="nofollow">LAMBDA: The Ultimate Imperative</a> says:</p>

<blockquote>
  <p>{Jensensdevice}</p>
  
  <p>The technique of repeatedly modifying a variable passed call-by-name in order to produce side effects on another call-by-name parameter is commonly known as Jensen's device, particularly in the case where call-by-name parameters are <em>j</em> and <em>a[j]</em>. <strong>We cannot find any reference to Jensen or who he was, and offer a reward for any information leading to the identification, arrest, and conviction of said Jensen.</strong></p>
</blockquote>

<p>Today, after almost 40 years since the memo was published, do we know the identity of Jensen? I'm not hoping for the reward, just curious.</p>

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2013-01-21T10:13:54.037Z
Did you read http://en.wikipedia.org/wiki/Jensen%27s_Device ?
Kristoffer Arnsfelt Hansen
CC BY-SA 3.0
2013-01-21T12:22:17.233Z
No, as you might guess from the question. I tried googling "Who is Jensen from Lambda the Ultimate" but it didn't cross my mind to just google "Jensen's device". I guess that was too simple :D
Jan Stolarek
<ho.history-overview>
Lambda: The Ultimate Imperative - who is Jensen?
Jan Stolarek
# Lambda: The Ultimate Imperative - who is Jensen?

(Asked by: username_0 on 2013-01-21)

One of the notes in the classical paper [LAMBDA: The Ultimate Imperative](http://repository.readscheme.org/ftp/papers/ai-lab-pubs/AIM-353.pdf) says:

> {Jensensdevice}
>
> The technique of repeatedly modifying a variable passed call-by-name in order to produce side effects on another call-by-name parameter is commonly known as Jensen's device, particularly in the case where call-by-name parameters are *j* and *a[j]*. **We cannot find any reference to Jensen or who he was, and offer a reward for any information leading to the identification, arrest, and conviction of said Jensen.**

Today, after almost 40 years since the memo was published, do we know the identity of Jensen? I'm not hoping for the reward, just curious.

**Tags:** ho.history-overview

> **Comments:**
> **username_1**: Did you read http://en.wikipedia.org/wiki/Jensen%27s_Device ?  
> **username_0**: No, as you might guess from the question. I tried googling "Who is Jensen from Lambda the Ultimate" but it didn't cross my mind to just google "Jensen's device". I guess that was too simple :D  

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## 1 answers

### Answer by username_0 on 2013-01-21. Score: 4 | Accepted answer

[Jensen's device](http://en.wikipedia.org/wiki/Jensen%27s_Device) was developed by [Jørn Jensen](http://en.wikipedia.org/wiki/J%C3%B8rn_Jensen), who worked on one of the earliest ALGOL 60 compilers (this answer is based on [comment by username_1](https://cstheory.stackexchange.com/questions/16158/lambda-the-ultimate-imperative-who-is-jensen#comment41960_16158)).


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