Branching

if

Classic. Executes a block if a test is true.

if <test> [ block ]

>> if 10 > 4 [print "large"]
large

unless

Same as if not. Executes block only if a test is false.

unless <test> [ block (if test false) ]

>> unless 10 > 4 [print "large"]
== none
>> unless 4 > 10 [print "large"]
large

either

A new name for the classic if-else. Executes the first block if the test is true or executes the second block if the test is false.

either <test> [true block] [false block]

>> either 10 > 4 [print "bigger"] [print "smaller"]
bigger
>> either 4 > 10 [print "bigger"] [print "smaller"]
smaller

switch

Executes the block correspondent to a given value.

twenty
>>

switch/default

If the program does not find a match, executes a default block.

none of them
>>

case

Makes a series of tests, executing the block corresponding to the first true test.

this is it!
>>

case/all

Executes all the true tests.

this is it!
also ok!
>>

catch & throw

Catch and throw may be used to create complex control structures. In its simplest form, catch receives a return from one of many throws:

just right
>>

Boolean branching

all

Evaluates all expressions in a block. If one evaluation returns false, it returns none, otherwise returns the result of the last evaluation.

>> john: "boy"
== "boy"
>> alice: "girl"
== "girl"
>> all [john = "boy" alice = "girl" 10 + 3]      ;all true, the last evaluation is returned.
== 13
>> all [john = "boy" alice = "boy" 10 + 3]       ; alice = "boy" is false!
== none

any

Evaluates each expression in a block in and returns the first resulting value that is not false. If all resulting values are false it returns none.

>> john: "boy"
== "boy"
>> alice: "girl"
== "girl"
>> any [john = "girl" alice = "girl" 10 + 3]      ;alice = "girl" is not false: return it!
== true
>> any [john = "girl"  10 + 3 5 > 2]              ; 10 + 3 is not false: return it!
== 13