How can you write multiple statements in elisp 'if' statement?

Question

In elisp, there is an 'if' case where I would like to perform many different things:

(if condition
    (do-something)
    (do-another-thing)
    ...)

However, (do-another-thing) is executed in the else-case only. How can you specify a block of instructions to execute? For example:

(if condition
    (begin
        (do-something)
        (do-another-thing)
        ...))

score 107 · Accepted Answer · edited Jan 07 '23 at 11:23

107

Use progn:

(if condition
    (progn
        (do-something)
        (do-another-thing)))

See sequencing in the manual.

edited Jan 07 '23 at 11:23

Mustafa Aydın

answered May 26 '09 at 19:53

mipadi

score 53 · Answer 2 · edited Jan 07 '23 at 11:18

53

If there's no else required, it might be more readable to use:

(when condition
    (do-something)
    (do-another-thing))

And, there's the converse

(unless (not condition)
    (do-something)
    (do-another-thing))

edited Jan 07 '23 at 11:18

Mustafa Aydın

answered May 26 '09 at 20:30

Trey Jackson

3

FWIW, I generally follow the convention suggested in *Common Lisp The Language* of using `when` and `unless` when the return value is not important (i.e., they are used for side effects only). I generally use `and` and `or` when the return value is important. I generally use `if` and `cond` when there are multiple branches (whether or not the return value is important). – Drew Oct 29 '13 at 01:07

2 Answers2