block or non-block ? I don't understand

[igouy]

example.toit:31:9: error: Argument mismatch for 'List.sort'
Argument '--in-place' was passed with block type, but must be non-block
  items.sort --in-place=: | a b | a[1] < b[1] ? 1 : -1
        ^~~~
Compilation failed

;but here =: seems required;

/opt/tmp/started$ /opt/src/toit/bin/toit.compile -o example example.toit
example.toit:36:38: error: Argument mismatch for 'Map.get'
Method does not take an unnamed block argument, but one was provided
Argument '--if-absent' was passed with non-block type, but must be block
  return (base_counts code.size seq).get code 
                                     ^~~
Compilation failed

By trial and error I figured out how to make it compile but it seems like both situations are the same?

example.txt

[kasperl]

So --in-place is a named boolean argument that you set to true and the block itself is an unnamed block argument. So the correct code is equivalent to this:

items.sort --in-place=true (: | a b | a[1] < b[1] ? 1 : -1)

For the --if-absent case, the argument is a named block argument, so you have to pass it a block. Blocks are stack-allocated and governed by special rules so they cannot outlive the surrounding method activation. You can read more about it here: https://docs.toit.io/language/blocks-and-lambdas.