PEP 312 - Making lambdas implicit worries me, surely it's just the name 'lambda' that is bad...

[Sean Ross]

How about "do", instead of "fn"?:

sum = do a, b: a + b

or,  if you want blocks,

total = do seq:
                amt = 0
                for i in seq:
                    amt += i
                return amt

This would be similar to ruby blocks, except there would be no end statement
and the block parameters would not be piped ( do |seq|: ... ).  I'm not sure
about
how to handle the indentation, i.e., should it be as above, where you indent
once
beyond "do" or

total = do seq:
    amt = 0
    for i in seq:
        amt += i
    return amt

where you indent once beyond the current indentation level.

Whatever...
just a passing thought,
Sean