Calling/applying lambda vs. function call - the syntax in Ruby is different. Why?
I am kinda new to Ruby and still trying to understand some of the language design principles. IF I've got it right, the lambda expression call in Ruby must be with square braces, while the "regular" function call is with "regular"/round braces.
Is there a special reason that the syntax is different? Or, in other words, (why) should the caller be aware whether they call a function or apply a lambda expression?
Answer
Regular Ruby method calls use () not curly braces which are for blocks. If you don't like [] for calling a lambda, you can always use the call method.
Example:
>> by_two = lambda { |x| x * 2 } #=> #<Proc:0x0000000101304588@(irb):1>
>> by_two[5] #=> 10
>> by_two.call(5) #=> 10
Edit
In newer version of Ruby also:
>> by_two.(5) #=> 10
As to why you can't just do by_two(5), when Ruby sees a bareword it first tries to resolve it as a local variable and if that fails as a method.