Integer return type not typecasted only when returning from function

Help & Support
1

I am trying some code snippets with Crystal 1.0.0 and observing this. I am not sure if this is expected behavior, if yes then any detail would be helpful to understand.

Why is 0 not getting typecasted to Float64 only while returning from a function, but assignment & as an argument is being accepted?

  1 def func1 ( a : Float64 )
  2   # Argument is accepted as Float64
  3   a
  4 end
  5 
  6 def func2 : Float64
  7   # Return type as Float64 is not accepted; Compilation error for func2
  8   0
  9 end
 10 
 11 c : Float64 = 0     # Assignment is accepted as Float64
 12 puts func1(0)
 13 puts func2

Compilation error:

In code2.cr:6:13

 6 | def func2 : Float64
                 ^------
Error: method top-level func2 must return Float64 but it is returning Int32

My crystal version - Debian Linux

Crystal 1.0.0 [dd40a2442] (2021-03-22)
LLVM: 10.0.0
Default target: x86_64-unknown-linux-gnu
2

Because that’s how the language works. It’s easy to see that you pass a number literal to a call. It’s harder to do that when a method can have multiple points where a value is returned.

3

That said, it might be a nice enhancement. But I’m not sure. It might be misleading if someone reads the code and see an integer being returned, and the return type is far away.

4

Thanks for the clarification. Coming from C/C++ world, I was expecting same rules for arguments vs return types, that the language would take care of typecasting. Just that I saw that rules seems differently applied in this usecase. May be a consistent behavior would be more logical, just my humble opinion.

5

“that’s how it works” wasn’t a nice answer. What I really meant is that right now it’s expected behavior :-)

6

Not an issue :slight_smile:
Appreciate your timely responses, very helpful for newbies like me. Thanks for your efforts!