Confusion - PowerQuery M Syntax for "in", and terminology

[ITookUrJob]

I am trying to understand syntax and terminology of M-language as I am new to its syntax.

let
    Source = #table(
    type table [OrderID = number, CustomerID = number, Item = text, Price = number],  
        {  
              {1, 1, "Fishing rod", 100.00},  
              {2, 1, "1 lb. worms", 5.00}  
         }
    )
in
    Source{1}

I am trying to understand couple of things of PowerQuery m language syntax:

• Does let statement decide the order displayed in "Applied steps" pane?

• What is the point of "in" statement if the last step is the final transformation to be evaluated anyway?

• Should I call each step in the "let" statement a function, or a variable (I am confused on terminology here). I understand Source is a variable, but its a function as well, correct if I am wrong on this.
Reply

 

[RoryA]

1. Everything starts with a Let, but not everything that appears after that and before the 'in' will necessarily be displayed as a step.
2. Everything ends with an 'in' which determines what the final output actually is (it doesn't actually have to be the last step in the Let sequence)
3. The part of each line before the = you can regard as a variable, the bit after it is the actual functional code (which can involve one or more functions)

 

[alansidman]

Expressions, values, and let expression - PowerQuery M

Learn more about: Expressions, values, and let expression

docs.microsoft.com