If - Function Summary

Summary:

If condition is TRUE, evaluates the block.

Usage:

if condition then-block

Arguments:

condition - The condition argument.

then-block - The then-block argument. (must be: block)

Refinements:

/else - If not true, evaluate this block

else-block - The else-block argument. (must be: block)

Description:

Skip the block if the value is FALSE. To select an alternate result (else) use the EITHER function. IF returns the value of the block it evaluated or NONE otherwise.

age: 4 if age > 3 [print "wine is ready"] wine is ready

print if age > 2 ["ready"] ready

print if age < 2 ["not ready"] none

A common error is to add a block without specifying /else or without using the EITHER function. The extra block gets ignored.

Related:

either - If condition is TRUE, evaluates the first block, else evaluates the second.
select - Finds a value in the series and returns the value or series after it.
switch - Selects a choice and evaluates what follows it.