Iterators and Loops

[ozra]

Iterators and Loops

First, a friendly message: most often you can solve things in a functional way, using map, fold, filter, etc. resort to such when possible, before reaching for "imperative style loops".

The Basics - The While Loop

The foundational structural imperative construct while likely needs no introduction. There is no do .. while, use explicit break condition in the loop instead.

x = 0
while x < 47
    do-stuff-with x
    x += 1

Func / Method and Soft Lambda Based Loops

All more complex iterators are implemented as funcs / methods taking a soft lambda (read #14 if you haven't already) as argument. The for-construct is syntactic sugar mapping to these methods.

list = [1, "foo", 3.14]

list.each |val|
  say val

list.each-with-index |val, ix|
   say "{val}, {ix}"

10.times |i|
    say i

(1..10).each |i|
    say i

(0...10).each |i|
    say i

For Loops

For-loops in Onyx is just sugar for calls to de facto named methods each, each-index or each-with-index, depending on which values are used. If the for-loop is kept in the language, it will likely be extended to handle more advanced iterations later on like SIMD-chunking etc.

[RFC] An abundance of notational styles are intially available - let's find the best fitting one and remove the others. Or - should it be kept at all? Simply stick to callables + soft lambdas and remove the for-construct completely?

list = [1, "foo", 3.14]

-- common variant, shown with two different nest starter tokens

for val in list => say val
for val, ix in list: say "{val}, {ix}"

for val in list
   say val

for val, ix in list
   say "{val}, {ix}"

for ,ix in list
   say ix

for n in 1..10
    say n

for n in 0...10
    say n

-- more esoteric variants, will likely be ditched!

for ix:val in list
   p "{val}, {ix}"

for ix: in list
   say ix

for val[ix] in list
   say "{val}, {ix}"

for [ix] in list
   say ix

[stugol]

I say keep the common variant. But without the => syntax option.

[ozra]

Noted.