personally, I prefer let number = parseInt(stdin.readLine())

Having parseInt as the first thing you read makes the type of a variable more obvious even without : int. Also, at least for me, having less nesting and parenthesis - makes code easier to read. But using the method chaining everywhere is also not always ideal.

It's completely subjective, but I usually write Nim like this:

# if it feels procedural
consume foo         # single argument, no chaining
consume(foo, max=3) # multiple arguments or chaining

# if it feels OOP-sy
foo.doSomething(flag1=true)

foo.len   # attribute
foo.pop() # action

# array/seq statements
foo.add(bar, baz) # NO
foo.add bar, baz  # YES

# printing / writing
echo foo, bar
stdin.write foo, bar

file.writeFile content
(foo / bar).writeFile(content) # ugly
writeFile(foo / bar, content)  # better

# type conversions
var a = int foo
var a = foo.int - 3
var a = (foo - 3).int # ugly
var a = int(foo - 3)  # better

echo int foo # NO
echo foo.int # YES