TLang.List

Creating Lists

      let fixed  = List.of("a", "b", "c")     // fixed list
      let empty  = List.create()               // empty list
      let with1  = List.push(empty, "item")   // ["item"]
    

Access and Info

      let n     = List.size(items)              // count
      let first = List.first(items)             // first element
      let last  = List.last(items)              // last element
      let el    = List.get(items, 2)            // element at index 2
      let has   = List.contains(items, "x")    // Bool
      let idx   = List.indexOf(items, "x")     // Int (-1 if not found)
    

Adding and Removing

      let pushed   = List.push(items, "new")           // append
      let prepended = List.prepend(items, "first")      // prepend
      let updated  = List.set(items, 1, "replaced")    // replace at index
      let removed  = List.remove(items, 2)             // remove at index
    

Slicing and Combining

      let tail    = List.tail(items)              // all but first
      let init    = List.init(items)              // all but last
      let sliced  = List.slice(items, 1, 3)       // elements 1..2
      let taken   = List.take(items, 3)           // first 3
      let dropped = List.drop(items, 2)           // skip first 2
      let rev     = List.reverse(items)
      let cat     = List.concat(a, b)             // join two lists
      let flat    = List.flatten(nested)          // one level flat
      let uniq    = List.distinct(items)
    

Sorting and Joining

      let sorted  = List.sort(items)                         // lexicographic
      let joined  = List.join(items, ", ")                   // "a, b, c"
      let zipped  = List.zip(keys, values)                   // List of pairs
    

Higher-Order Functions

All HOFs accept a lambda or function reference and work as both free functions and dot-method calls.

      // map — transform each element
      let doubled = List.map(nums, (x) => x * 2)
      let doubled = nums.map((x) => x * 2)

      // filter — keep matching elements
      let evens = List.filter(nums, (x) => x % 2 == 0)

      // forEach — side effect per element (returns Unit)
      List.forEach(items, (x) => Terminal.println(x))

      // reduce — fold left to a single value
      let sum = List.reduce(nums, 0, (acc, x) => acc + x)

      // any / all — boolean tests
      let hasNeg = List.any(nums, (x) => x < 0)
      let allPos = List.all(nums, (x) => x > 0)

      // find — first match or Unit
      let found = List.find(items, (x) => x.startsWith("A"))

      // count — count matching elements
      let n = List.count(items, (x) => x != "")

      // flatMap — map then flatten one level
      let words = List.flatMap(sentences, (s) => s.split(" "))

      // sortBy — sort by derived key
      let sorted = List.sortBy(users, (u) => u.name)

      // groupBy — group into a Map of lists
      let byFirstChar = List.groupBy(names, (n) => n.substring(0, 1))
    

Chaining

      let result = items
          .filter((x) => x != "")
          .map((x) => x.trim())
          .map((x) => Naming.toPascalCase(x))