ability to examine declared functions for runtime checks

[gfogle]

one of the main selling points of flow is that it can examine your functions - so to speak - to make sure your function always returns a value etc to eliminate runtime exceptions

ideally we should be able to do this.

[trezm]

I think this issue is basically this #9 right? Or is it a little more involved?

At the moment the checker does two checks; it checks variable declarations (i.e. var n /* t:number */ = 'asdf' and function declarations on the root scope and then follows the rabbit hole. For example, this error is caught:

function d(x /* t:string */) /* t:string */ {       
  function e(y /* t:string */) /* t:string */ {     
    function f(z /* t:string */) /* t:number */ {   
      return y + x + z;                             
    }                                               

    return f(y);                                    
  }                                                 

  return e(x);                                      
}

Am I misunderstanding or are you basically saying that we should check for undefined/null variables?

[gfogle]

i think #9 might be it then. We just want to make sure that the following errors for this function are caught:

function (e /* t:int */) /* t: int */ {
  if (e > 2 && e < 5) {
     return e + 2;
  } else if (e >= 5) {
     return 'a string?';
  }
}

in the case where e < 2 nothing will be returned, and in the case where e >=5 a string is returned instead of a number.

maybe i misunderstood #9 its description is a little verbose

[trezm]

Oh, I see what you're saying, I think #9 only partially covers this
situation, I.e. the returning undefined one. This issue is still valid for
the "could be a string could be a number" situation though.

On Sun, Sep 18, 2016, 10:19 AM George Fogle notifications@github.com
wrote:

i think #9 #9 might be it then.
We just want to make sure that the following errors for this function are
caught:

function (e /* t:int /) / t: int */ {
if (e > 2 && e < 5) {
return e + 2;
} else if (e >= 5) {
return 'a string?';
}
}

in the case where e < 2 nothing will be returned, and in the case where e

=5 a string is returned instead of a number.

maybe i misunderstood #9 #9

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