8 ms·

<~ looks like an expression for a bulk update of an immutable record. "point.y = value" is typically a statement for a single update of a mutable record. I'm

by ken 8y ago

<~ looks like an expression for a bulk update of an immutable record. "point.y = value" is typically a statement for a single update of a mutable record. I'm not sure how you'd extend the latter to support the features of the former. The meaning is completely different. Different things should look different.

auggierose 8y ago
I think this is nicely solved in Swift.
- ken 8y ago
  How? I don't know any way to do a bulk update of an immutable structure in Swift, apart from constructing an entirely new structure and passing all values (not just changed ones) to its initializer.
  - auggierose 8y ago
    You can just declare all members of the structure as vars. The structure will still be immutable.
pmontra 8y ago
I expand a little my point. This is from Elixir, functional and immutable, which I've been working with for a couple of years iex(1)> point = %{x: 1, y: 2, z: 3} %{x: 1, y: 2, z: 3} Of course this doesn't work iex(2)> point.x = 4 ** (CompileError) iex:2: cannot invoke remote function point.x/0 inside match This is how we do it, verbosely iex(3)> Map.put(point, :x, 4) %{x: 4, y: 2, z: 3} Or with a syntax shortcut iex(4)> %{point | x: 4} %{x: 4, y: 2, z: 3} A better syntax shortcut would be the usual iex(nope)> point.x = 4 %{x: 4, y: 2, z: 3} which everybody would understand no matter the language of origin. I imagine that it would require quite an overhaul of the internals of the compiler, but the compiler should bend to us, not us to the compiler. This is my point about obscure language syntaxes.
- Ndymium 8y ago
  The problem with the last code snippet is that it looks like mutating the original value, and that would mislead newcomers to the language.
  - pmontra 8y ago
    Yes, that's possible. However this is an example from Ruby, which is very mutable but has some immutable features in its standard library. 2.3.0 :001 > s = "abc" => "abc" 2.3.0 :002 > s.gsub("b", "B") => "aBc" 2.3.0 :003 > s => "abc" 2.3.0 :004 > s.gsub!("b", "B") => "aBc" 2.3.0 :005 > s => "aBc" I guess that if an immutable language shows some mutable syntax we can expect it to be a short form. Actually Elixir has at least a mutable short form: iex(1)> s = "abc" "abc" iex(2)> String.replace(s, "b", "B") "aBc" iex(3)> s "abc" The next line would be an error in Erlang and other languages because we can't mutate an already assigned variable there, but Elixir allows rebinding iex(4)> s = String.replace(s, "b", "B") "aBc" iex(5)> s "aBc"
- ken 8y ago
  I would not understand that. In every language I've used that supported "point.x = 4", the returned value (if there is one) is 4, not point. Bosque's update is more like CONS (or conj) than . = Your proposed syntax also doesn't have any obvious way to do a bulk update, and I'm not sure what syntax you're proposing for that. I maintain that it's more important for things to look like how they act, rather than look familiar -- especially if the familiar appearance does something functionally different -- https://stackoverflow.com/a/522168 https://stackoverflow.com/a/522168

by ken 8y ago

auggierose 8y ago

I think this is nicely solved in Swift.

ken 8y ago
How? I don't know any way to do a bulk update of an immutable structure in Swift, apart from constructing an entirely new structure and passing all values (not just changed ones) to its initializer.
- auggierose 8y ago
  You can just declare all members of the structure as vars. The structure will still be immutable.

pmontra 8y ago

I expand a little my point. This is from Elixir, functional and immutable, which I've been working with for a couple of years iex(1)> point = %{x: 1, y: 2, z: 3} %{x: 1, y: 2, z: 3} Of course this doesn't work iex(2)> point.x = 4 ** (CompileError) iex:2: cannot invoke remote function point.x/0 inside match This is how we do it, verbosely iex(3)> Map.put(point, :x, 4) %{x: 4, y: 2, z: 3} Or with a syntax shortcut iex(4)> %{point | x: 4} %{x: 4, y: 2, z: 3} A better syntax shortcut would be the usual iex(nope)> point.x = 4 %{x: 4, y: 2, z: 3} which everybody would understand no matter the language of origin. I imagine that it would require quite an overhaul of the internals of the compiler, but the compiler should bend to us, not us to the compiler. This is my point about obscure language syntaxes.

Ndymium 8y ago
The problem with the last code snippet is that it looks like mutating the original value, and that would mislead newcomers to the language.
- pmontra 8y ago
  Yes, that's possible. However this is an example from Ruby, which is very mutable but has some immutable features in its standard library. 2.3.0 :001 > s = "abc" => "abc" 2.3.0 :002 > s.gsub("b", "B") => "aBc" 2.3.0 :003 > s => "abc" 2.3.0 :004 > s.gsub!("b", "B") => "aBc" 2.3.0 :005 > s => "aBc" I guess that if an immutable language shows some mutable syntax we can expect it to be a short form. Actually Elixir has at least a mutable short form: iex(1)> s = "abc" "abc" iex(2)> String.replace(s, "b", "B") "aBc" iex(3)> s "abc" The next line would be an error in Erlang and other languages because we can't mutate an already assigned variable there, but Elixir allows rebinding iex(4)> s = String.replace(s, "b", "B") "aBc" iex(5)> s "aBc"
ken 8y ago
I would not understand that. In every language I've used that supported "point.x = 4", the returned value (if there is one) is 4, not point. Bosque's update is more like CONS (or conj) than . = Your proposed syntax also doesn't have any obvious way to do a bulk update, and I'm not sure what syntax you're proposing for that. I maintain that it's more important for things to look like how they act, rather than look familiar -- especially if the familiar appearance does something functionally different -- https://stackoverflow.com/a/522168 https://stackoverflow.com/a/522168