Swift Control Flow using Loops
One of Swifts strengths is clear, readable INTENT, conveyed by the languages
Keyword tokens. For anyone new to programming, clear, readable intent, goes a
long way in helping them master the language, by helping reduce
logical/semantic errors caused by a misunderstanding of the names used in
specifying the languages keyword tokens…
Swift’s control flow keywords can be ambiguous, in this respect, when conveying
the functional intent of loop control logic, within the language.
I would like to open up discussion, therefore, regarding the possible renaming
of Swift’s control flow keywords, with the hope that this leads to clearer
INTENT regarding loops.
Replace For-In with Loop Using
for foo in d…y loop foo using d…y
For x in 1…5 loop x using 1…5
loop i=0 using i<10
loop i using 0..<10
For _ in 1 …power ———-> loop using 1…power
“The underscore character (_) used in place of a loop variable causes the
individual values to be ignored and does not provide access to the current
value during each iteration of the loop.”
I feel underscore character (_) is confusing, semantically.
let names = ["Anna", "Alex", "Brian", “Jack"]
for name in names { ———-> loop names using name {
print("Hello, \(name)!")
}
Note : loop ARRAY using ELEMENT(S) - which is logically consistent with
‘-using’ as last keyword instance.
let numberOfLegs = ["spider": 8, "ant": 6, "cat": 4]
for (animalName, legCount) in numberOfLegs {
print("\(animalName)s have \(legCount) legs")
}
loop numberOfLegs using (animalName, legCount) {
print(“ \(animalName)s have \(legCount) Legs”)
}
Note : Again loop ARRAY using ELEMENT(S) - which is logically consistent with
‘-using’ as last keyword instance.
for (airportCode, airportName) in airports {
loop airports using (airportCode, airportName)
for airportCode in airports.keys {
loop airports.keys using airportCode {
for airportName in airports.values {
loop airports.values using airportName {
for value in array[1..<array.count] {
loop array[1..<array.count] using value
‘while’ using loop while
loop while square < finalSquare {
// roll the dice
diceRoll += 1
if diceRoll == 7 { diceRoll = 1 }
// move by the rolled amount
Control transfer statements
repeat { ——> loop {
…
} while
“Break
The break statement ends execution of an entire control flow statement
immediately. ”
I propose replacing Break, in loops, with exit now (intent is explicit)
Note: Labeled Statements with break -
break gameLoop exit now gameLoop
“Continue
The continue statement tells a loop to stop what it is doing and start again at
the beginning of the next iteration through the loop.”
“switch character {
case "a", "e", "i", "o", "u", " ":
continue // Continue what? to next line? to end? to beginning?
default:
puzzleOutput.append(character)
}”
I propose replacing continue with next cycle or next loop
“switch character {
case "a", "e", "i", "o", "u", " ":
next cycle // intent is explicit
default:
puzzleOutput.append(character)
}”
Note: Labeled Statements with Continue - as per Break example, next cycle
gameLoop
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