Ranges, Lists, and Maps

Basic Syntax: Ranges, Lists, and Maps

III. Ranges, Lists, and Maps

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1. Ranges

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• Range expressions Ranges use ..< (left-closed, right-open) or .. (closed range), with no spaces on either side. Variable expansion is supported.

  10..<10        # does not include 10
  20..10         # includes 10
  3a..b

  Range expressions support stepping: :step

  10..6:2        # indicates a step of 2: [0,2,4,6]

  Can be used for loops, containment checks, array creation, etc.

  1let r = 0..8
  2
  3for i in r {...}       # more efficient than looping directly on an array
  4r ~: 5                 # check if it contains an element
  5List.from(r)           # convert to an array

2. Lists (Arrays)

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• Lists are represented with [ ]. The internal elements are ordered.

• They can also be created directly from ranges using ... or ...<

  10...5               # outputs [0,1,2,3,4]
  2# equivalent to
  3List.from(0..5)

Two dots .. ..< create ranges, while three dots ... ...< create arrays.

• Indexing is represented with . or [i].

  1let arr = [10, "a", True]

• Indexing and Slicing

  1# Basic indexing
  2
  3arr.1
  4arr[0]       # → 10
  5
  6# Slicing operations
  7arr[1:3]     # → ["a", True] (left-closed, right-open)
  8arr[::2]     # → [10, True] (step of 2)
  9arr[-1:]     # → True (slicing supports negative indexing)

• Complex Nesting

  1# Complex nesting
  2[1,24,5,[5,6,8]][3][1]     # displays 6
  3# Modify element
  4# arr[2] = 3.14 # → [10, "a", 3.14]

• Advanced Operations Refer to the list module.

Edge Cases:

• Array indexing that exceeds bounds will trigger an out of bounds error.
• Array slicing supports negative numbers, indicating indices counted from the end.
• Indexing on non-indexable objects will trigger the following error: [ERROR] type error: expected indexable type (list/dict/string), found symbol

3. Maps (Dictionaries)

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• Maps are represented with {}

   1let mydict = {name: "Alice", age: 30}
   2
   3# Allows shorthand:
   4let a = b = 3,
   5{a, b}
   6{
   7    a,
   8    b,
   9}          # allows trailing commas, allows multi-line writing
  10{a, }             # trailing comma for a single key-value cannot be omitted

• Dictionary Indexing

   1# Basic access
   2
   3mydict["name"]     # → "Alice"
   4mydict.name        # → "Alice" (shorthand)
   5mydict@name        # → "Alice" (shorthand)
   6
   7# Dynamic key support
   8let key = "ag" + "e"
   9dict[key]       # → 30
  10
  11# Nested access
  12let data = {user: mydict}
  13data.user.age # → 100

• Advanced Operations Refer to the map module.

Edge Cases: