Re: [External] : Re: [ELPA] New package: listen

[Adam Porter <adam@alphapapa.net>]

On 2/26/24 11:17, Drew Adams wrote:

> There's no separation of return value from
> conditions in `when' - it simply always
> returns `nil'.  It has only one condition,
> the body has no bearing on the return value
> (unless it `throw's etc.).
> 
> The visual separation of condition code and
> body is irrelevant to the logical separation
> of condition and return value.  The body's
> irrelevant to the return value.

According to elisp.info:

> when is a Lisp macro in ‘subr.el’.
> 
> (when COND &rest BODY)
> 
> If COND yields non-nil, do BODY, else return nil.
> When COND yields non-nil, eval BODY forms sequentially and return
> value of last one, or nil if there are none.

According to CLHS:

> In a when form, if the test-form yields true, the forms are evaluated in order from left to right and the values returned by the forms are returned from the when form. Otherwise, if the test-form yields false, the forms are not evaluated, and the when form returns nil.