unless

unless( 
g_condition 
g_expr1 ... 
) 
=> g_result / nil 

Description

Evaluates a condition. If the result is true (non-nil), it returns nil; otherwise evaluates the body expressions in sequence and returns the value of the last expression. This is a syntax form.

The semantics of this function can be read literally as "unless the condition is true, evaluate the body expressions in sequence".

Arguments

g_condition	Any SKILL expression.
g_expr1	Any SKILL expression.

Value Returned

g_result	Value of the last expression of the sequence g_expr1 if g_condition evaluates to nil.
nil	If g_condition evaluates to non-nil.

Examples

x = -123
unless( x >= 0 println("x is negative") -x)
=> 123            ;Prints "x is negative" as side effect.

unless( x < 0 println("x is positive") x)
=> nil

Related Topics

Flow Control Functions

cond

if

when

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