Jonathan Lamothe

me@social.jlamothe.net

Programmer and free/libre software enthusiast. This is my primary account on the Fediverse. See my website for an authoritative list of accounts.
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Ontario, Canada

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Jonathan Lamothe

2 weeks ago

Jonathan Lamothe
2 weeks ago

A question for the #lisp folx:
What, if anything, is the difference between #'(lambda ...) and just plain (lambda ...)?

They seem functionally equivalent to me.

#lisp

in reply to Jonathan Lamothe

royae

in reply to Jonathan Lamothe 2 weeks ago

It is only relevant in a lisp2.
(lambda ...) is just a macro call that expand in the other form.
From the common lisp spec :

(lambda lambda-list [[declaration* | documentation]] form*)
 ==  (function (lambda lambda-list [[declaration* | documentation]] form*))
 ==  #'(lambda lambda-list [[declaration* | documentation]] form*)

in reply to Jonathan Lamothe

Dave Tenny

in reply to Jonathan Lamothe 2 weeks ago

lambda returns a function, so the symbol-function syntax is redundant now. It wasn't always that way in CL's history. Anyway, no need to use #' with lambda now.

in reply to Jonathan Lamothe

Holger

in reply to Jonathan Lamothe 2 weeks ago

in common lisp I think the #‘ should be redundant for lambdas. But I haven’t touched common lisp in years so I hope i remember right.

in reply to Jonathan Lamothe

Pascal Costanza

in reply to Jonathan Lamothe 2 weeks ago

Yes, functionally equivalent. (lambda …) was a late addition to #CommonLisp to make it more compatible with #ISLisp

#commonlisp #islisp

in reply to Jonathan Lamothe

Svante

in reply to Jonathan Lamothe 2 weeks ago

Seemingly plain (lambda () ...) is a macro that expands to (function (lambda () ...)). #'(lambda () ...) uses a reader macro to expand to the same (function (lambda () ...)).

clhs.lisp.se/Body/m_lambda.htm

Function is a special operator that returns a function. It takes either a function name or a lambda expression. The second case is what is happening here.

clhs.lisp.se/Body/s_fn.htm#fun…

A lambda expression is a list of the symbol lambda, a lambda list, and a body.

clhs.lisp.se/Body/26_glo_l.htm…