Implementing `let` without using a macro

Posted by Matt Fenwick on Programmers See other posts from Programmers or by Matt Fenwick
Published on 2012-07-02T00:31:52Z Indexed on 2012/07/02 15:23 UTC
Read the original article Hit count: 199

Filed under:

language-design

|

lisp

I'm learning Lisp, and I've just gotten to let, which I don't quite understand (the implementation of).

A common definition for it is given in terms of lambda as a macro. However, nowhere have I seen that let must be implemented as a macro or in terms of lambda.

Is it possible to define let without using a macro or lambda?

I know it can be implemented as a primitive, but I want to know whether it can be implemented in Lisp without creating a macro -- by creating a special form or a function.

© Programmers or respective owner

Related posts about language-design

From a language design perspective, if Javascript objects are simply associative arrays, then why ha

as seen on Stack Overflow - Search for 'Stack Overflow'
I was reading about objects in O'Reilly Javascript Pocket Reference and the book made the following statement. An object is a compound data type that contains any number of properties. Javascript objects are associative arrays: they associate arbitrary data values with arbitrary names. From… >>> More
Language Design: Combining Gotos and Functions

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm designing and currently rethinking a low-level interpreted programming language with similarities to assembler. I very soon came across the functions/loops/gotos decision problem and thought that while loops like while and for would be too high-level and unfitting, gotos would be too low level… >>> More
Missing ideas in programming language design

as seen on Stack Overflow - Search for 'Stack Overflow'
I wanted to try something new and so I designed some programming languages and wrote interpreters for them: A rather low-level, not very expressive language. (I didn't want to parse complex expressions right at the beginning) It featured: Variables (yay) Subroutines, with a call stack Basic… >>> More
New book in the style of Advanced Programming Language Design by R. A. Finkel [closed]

as seen on Programmers - Search for 'Programmers'
I am currently researching visual programming language design for a university paper and came across Advanced Programming Language Design by Raphael A. Finkel from 1996. Other, older discussions in the same vein on Stackoverflow have mentioned Language Implementation Patterns by Terence Parr and… >>> More
C# language design pillars

as seen on Stack Overflow - Search for 'Stack Overflow'
In the article (http://www.artima.com/intv/nonvirtualP.html) Anders Hejlsberg mentioned that versioning is one of the pillars of C# language design. Does anybody know what are other pillars? >>> More

Related posts about lisp

Why is Lisp useful?

as seen on Programmers - Search for 'Programmers'
Lisp obviously is an advantage for the AI stuff but it doesn't appear to me that Lisp is any faster than Java, C#, or even C. I am not a master of Lisp, but I find it incredibly difficult to understand the advantage one would get in writing Business Software in Lisp. Yet it is considered as a hacker's… >>> More
Why do you like Lisp ?

as seen on Programmers - Search for 'Programmers'
Why does Paul Graham advocate Lisp? Why did ITA Software choose Lisp over other High Level languages? Lisp obviously is an advantage for the AI stuff but I don't think Lisp is any faster than Java, C# or as a matter of fact faster than C. Still it is considered as a Hackers language? I am not a master… >>> More
Emacs 23.1 make error 139 in Mac OS X 10.6.3

as seen on Stack Overflow - Search for 'Stack Overflow'
When I try to compile GNU Emacs 23.1 on my machine with Mac OS X 10.6.3 I repeatedly get the following ending: Directories: /src/emacs-23.1/lisp/. /src/emacs-23.1/lisp/./calc /src/emacs-23.1/lisp/./calendar /src/emacs-23.1/lisp/./emacs-lisp /src/emacs-23.1/lisp/./emulation /src/emacs-23.1/lisp/./erc… >>> More
Why not port Linux kernel to Common Lisp?

as seen on Stack Overflow - Search for 'Stack Overflow'
Conventional wisdom states that OS kernels must be written in C in order to achieve the necessary levels of performance. This has been the justification for not using more expressive high level languages. However, for a few years now implementations of Common Lisp such as SBCL have proven to be… >>> More
Lisp Style question label local functions or not?

as seen on Stack Overflow - Search for 'Stack Overflow'
I was wondering if there is a standard practice regarding the use of labels in Lisp. I've been messing around with a Lisp implementation of the algorithm described in the first answer here http://stackoverflow.com/questions/352203/generating-permutations-lazily My current version uses labels to… >>> More