Skip to main content

Range

rascal-0.40.17

Synopsis​

Numeric range of values.

Syntax​

  • [ Exp₁ .. Exp₃ ]
  • [ Exp₁, Exp₂ .. Exp₃ ]

Description​

Ranges are a shorthand for describing lists of integers from Exp₁ up to (exclusive) Exp₃ with increments of 1. When Exp₂ is present it is taken as the second element of the list and Exp₂ - Exp₁ is used as increment for the subsequent list elements.

A range with integer expressions is identical to a list Slice. However, a range may also contain numeric expressions that are not integers.

Examples​

rascal>[1 .. 10];
list[int]: [1,2,3,4,5,6,7,8,9]
rascal>[1, 3 .. 10];
list[int]: [1,3,5,7,9]
rascal>[0.5, 3.2 .. 10];
list[real]: [0.5,3.2,5.9,8.6]
rascal>[1, -2 .. -10];
list[int]: [1,-2,-5,-8]

Benefits​

Ranges are mostly used to loop over ranges of integers.

Pitfalls​

In some cases ranges are empty where one could have expected at least one element:

rascal>[1, 3 .. -10];
list[int]: []