lyng/docs/Range.md

Range

Range is diapason between two values. Open range has at least one end open, e.g. ±∞, closed range has both ends open.

Closed ranges

The syntax is intuitive and adopted from Kotlin:

// end inclusive:
val r = 1..5
assert(5 in r)
assert(6 !in r)
assert(0 !in r)
assert(2 in r)
>>> void

Exclusive end ranges are adopted from kotlin either:

// end inclusive:
val r = 1..<5
assert(5 !in r)
assert(6 !in r)
assert(0 !in r)
assert(2 in r)
assert(4 in r)
>>> void

In any case, we can test an object to belong to using in and !in and access limits:

val r = 0..5
(r.end - r.start)/2
>>> 2

Notice, start and end are ints, so midpoint here is int too.

It is possible to test that one range is included in another range too, one range is defined as contained in another ifm and only if, it begin and end are equal or within another, taking into account the end-inclusiveness:

assert( (1..3) in (1..3) )
assert( (0..3) !in (1..3) )
assert( (1..2) in (1..<3) )
assert( (1..<2) in (1..<3) )
assert( (1..<3) in (1..3) )
>>> void

Range size and indexed access

This might be confusing, but the range size and limits are used with for loops so their meaning is special.

For open ranges, size throws and exception.

For Int ranges, the size is end - start possibly + 1 for ind-inclusive ranges, and indexing getter returns all values from start to end, probably, inclusive:

val r = 1..3
assert( r.size == 3 )
assert( r[0] == 1 )
assert( r[1] == 2 )
assert( r[2] == 3 )
>>> void

And for end-exclusive range:

val r = 1..<3
assert(r.size == 2)
assert( r[0] == 1 )
assert( r[1] == 2 )
>>> void

In spite of this you can use ranges in for loops:

for( i in 1..3 ) 
    println(i)
>>> 1
>>> 2
>>> 3
>>> void

but

for( i in 1..<3 ) 
    println(i)
>>> 1
>>> 2
>>> void

Instance members

member	description	args
contains(other)	used in in	Range, or Any
isEndInclusive	true for '..'	Bool
isOpen	at any end	Bool
isIntRange	both start and end are Int	Bool
start		Bool
end		Bool
size	for finite ranges, see above	Long
[]	see above