Conditional structures: Difference between revisions

=={{header|Picat}}==

Picat is a multi-paradigm language (based on Prolog) and has some different conditional structures:

* "direct" testing: The program will not continue if not satisfied.

* <code>if/then/elseif/else/end</code>: Traditional if/then/else construct.

* <code>(condition -> then-part ; else-part)</code>: From Prolog.

* <code>Ret = cond(condition,then-part,else-part)</code>: Function which returns the appropriate value.

* As a predicate: From Prolog.

* As condition in a function's head.

Here are examples of each of these constructs.

<lang Picat>go =>

N = 10,

% "direct" test that will fail if not satisfied

N < 14,

% if/then/elseif/else

if N < 14 then

println("less than 14")

elseif N == 14 then

println("is 14")

else

println("not less than 14")

end,

% From Prolog: (condition -> then ; else)

( N < 14 ->

println("less than 14")

;

println("not less than 14")

),

% Ret = cond(condition, then, else)

println(cond(N < 14, "less than 14", "not less than 14")),

% as a predicate

test_pred(N),

% as condition in a function's head

println(test_func(N)),

println(ok), % all tests are ok

nl.

% as a predicate

test_pred(N) ?=>

N < 14,

println("less than 14").

test_pred(N) =>

N >= 14,

println("not less than 14").

% condition in function head

test_func(N) = "less than 14", N < 14 => true.

test_func(_N) = "not less than 14" => true. </lang>

{{out}}

<pre>less than 14

less than 14

less than 14

less than 14

less than 14

ok</pre>