On Wed, Jul 18, 2018, 1:55 PM James Reeves <ja...@booleanknot.com> wrote:
> On Wed, 18 Jul 2018 at 19:38, Gregg Reynolds <d...@mobileink.com> wrote:
>
>>
>> On Tue, Jul 17, 2018, 4:11 PM James Reeves <ja...@booleanknot.com> wrote:
>>
>>>
>>> A data literal evaluates to itself. So for example, `2` is a literal,
>>> because we only need to read it to know its value, whereas `(+ 1 1)`
>>> isn't a literal, because we also need to evaluate it to work out the value.
>>>
>>
>> Fair enough. But by that definition function expressions are also
>> literals.
>>
>
> Not at all:
>
> user=> (defn literal? [s] (let [e (read-string s)] (= e (eval e))))
> #'user/literal?
> user=> (literal? "2")
> true
> user=> (literal? "(fn [x] x)")
> false
> user=> (literal? "#(%)")
> false
> user=> (literal? "+")
> false
>
> Function expressions don't evaluate to themselves.
>
To me that means either the definition is wrong or your literal? is rigged.
Probably the latter; "literal" is meta, it can't be in the language.
Look at it this way: the meaning ("value") of "lambda x.x+1" is just the
function that increments its arg. Of course you have to "evaluate" to know
that, but you also have to evaluate "2" in the same way to know what it
means. Meaning "reduce", and neither form can be further reduced.
Anyway my point is that clojure, like lisp, is a form of the lambda
calculus, where everything is a function, even the Nats like 2. To me at
least that is one of the most important lessons of functional programming.
Ymmv.
--
You received this message because you are subscribed to the Google
Groups "Clojure" group.
To post to this group, send email to clojure@googlegroups.com
Note that posts from new members are moderated - please be patient with your
first post.
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
---
You received this message because you are subscribed to the Google Groups
"Clojure" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to clojure+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
