FOR 'word start end bump body

Repeats a block over a range of values.

FOR is a function value.

• word -- Variable to hold current value (Type: word)
• start -- Starting value (Type: number series money time date char)
• end -- Ending value (Type: number series money time date char)
• bump -- Amount to skip each time (Type: number money time char)
• body -- Block to evaluate (Type: block)

• catch
• throw

for: func [    "Repeats a block over a range of values."     [catch throw]     'word [word!] "Variable to hold current value"     start [number! series! money! time! date! char!] "Starting value"     end [number! series! money! time! date! char!] "Ending value"     bump [number! money! time! char!] "Amount to skip each time"     body [block!] "Block to evaluate"     /local result do-body op][    if (type? start) <> (type? end) [        throw make error! reduce ['script 'expect-arg 'for 'end type? start]    ]     do-body: func reduce [[throw] word] body     op: :greater-or-equal?     either series? start [        if not same? head start head end [            throw make error! reduce ['script 'invalid-arg end]        ]         if (negative? bump) [op: :lesser?]         while [op index? end index? start] [            set/any 'result do-body start             start: skip start bump        ]         if (negative? bump) [set/any 'result do-body start]    ] [        if (negative? bump) [op: :lesser-or-equal?]         while [op end start] [            set/any 'result do-body start             start: start + bump        ]    ]     get/any 'result]

• Book:Rebol Programming