Flutter: Illustrate List of Strings with a for-Loop doesn't work

Question

I am really confused why does this only work without the braces around the for-Loop.

        child: SingleChildScrollView(
          child: Column(
            children: [
              for (int i = 1; i < lst.length; i++)
                {
                  Container(
                    child: Card(
                      child: Text(lst[1]),
                    ),
                  )
                }
     ...

Answer 1

These are for statements:

for (var i = 0; i < 10; i += 1)
  print(i);

var someList = <int>[];
for (var i = 0; i < 10; i += 1) {
  someList.add(i);
  print(i);
}

Statements typically end with semicolons, and curly braces can group statements together. Statements do something.

You're not using a for statement; you're using Dart's "collection-for" syntax, which isn't actually a statement at all, nor does it contain any statements. It's an expression, and its body must also be an expression (or rather, an "element"). Expressions evaluate to a value that is consumed by other expressions (and usually ultimately to a statement).

Since collection-for does not contain statements, braces are inappropriate (ditto for collection-if), and the extraneous braces instead will be treated as creating a Set literal.

I highly recommend reading the Making Dart a Better Language for UI article which describes the motivation and design of collection-for and collection-if.

Answer 2

That's just a matter of a syntax. Normal for loop in normal inline code works perfectly, but you use a special for operator in a dart collection. Same case with if statements.