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### Why first lambda expression is args

Posted: **Mon Jul 06, 2015 8:52 am**

by **ssqq**

I think first lambda expression should is 'lambda:

Code: Select all

```
> (first (lambda (x y) (+ x y)))
lambda
> (first (fn (x y) (+ x y)))
fn
> 'lambda
lambda
> 'fn
fn
> (cons 'fn '((x y) (+ x y)))
(fn (x y) (+ x y))
```

Why newLISP use args as first elements of lambda expression?

Why could not quote *lambda* and *fn*?

### Re: Why first lambda expression is args

Posted: **Fri Oct 02, 2015 1:38 pm**

by **hartrock**

ssqq wrote:I think first lambda expression should is 'lambda:

Code: Select all

```
> (first (lambda (x y) (+ x y)))
lambda
> (first (fn (x y) (+ x y)))
fn
> 'lambda
lambda
> 'fn
fn
> (cons 'fn '((x y) (+ x y)))
(fn (x y) (+ x y))
```

Why newLISP use args as first elements of lambda expression?

Why could not quote *lambda* and *fn*?

**lambda** is a property of a list, and

*not* a symbol at its beginning; an example:

Code: Select all

```
> (set 'li (cons '(x y) (cons '(+ x y) '())))
((x y) (+ x y))
> (first li)
(x y)
> (set 'la (cons '(x y) (cons '(+ x y) '(lambda))))
(lambda (x y) (+ x y))
> (first la)
(x y)
>
```

-> both list and

**lambda** list having (x y) as first element.

But only the

**lambda** list works as function:

Code: Select all

```
> (li 3 4)
ERR: invalid list index
> (la 3 4)
7
>
```

From the manual

http://www.newlisp.org/downloads/newlisp_manual.html#fn:

... The fn or lambda word does not exist on its own as a symbol, but indicates a special list type: the lambda list. ...