ncalm

(LeftTable as table, JoinColumns as list, RightTable as table, optional JoinColumnsRight as list, 
optional DuplicateColumnPrefix as text, optional JoinKind as number) => 
let

    //a function to handle null (optional) parameters
    fnIfNull = (arg1, arg2) => if arg1 = null then arg2 else arg1,

    //if join kind is null, default to inner join
    _JoinKind = fnIfNull(JoinKind, JoinKind.Inner),

ncalm

/*
Note, this function is used by the functions in the graph namespace
*/
IFOMITTED = LAMBDA(arg, then, [else],
    LET(_else, IF(ISOMITTED(else), arg, else), IF(ISOMITTED(arg), then, _else))
);

ncalm

/*
A simple query to get the list of enumerations
*/
let
    Source = Web.Page(Web.Contents("https://learn.microsoft.com/en-us/powerquery-m/enumerations")){0}[Data]
in
    Source

ncalm

(typeTable as table) as list
    =>
    let
        //check that the columns in the supplied table have the expected names
        checkColumnNames = Table.ColumnNames(typeTable) = {"ColumnName","Type"},

        /*
        primitive types use this format in TransformColumnTypes
        type typeName
        Listed here are most common formats - full list on this page:

ncalm

(parameterName as text) as table =>
let
    Source = Record.ToTable(#shared),
    AddColumn = Table.AddColumn(
        Source,
        "Params",
        each try Text.Combine(Record.FieldNames(Type.FunctionParameters(Value.Type([Value]))),", ") otherwise null
    ),
    Result = Table.SelectRows(AddColumn, each Text.Contains([Params],parameterName))
in

ncalm

/*
Creates an empty array of r rows and c columns

Author: Owen Price
Date: 2022-09-14
*/
EMPTYARRAY = LAMBDA(r, [c], EXPAND({""}, r, IF(ISOMITTED(c), 1, c), ""));

/*
CROSSJOIN creates the cross-product of two arrays

ncalm

/*
from is the first integer in the list
to is the target integer in the list
step is the difference between successive integers
*/
L =LAMBDA(from,to,[step],
    LET(
        _step, IF(ISOMITTED(step), IF(from > to, -1, 1), step), 

        //arguments should be single integers

ncalm

/*
array is a column of stuff to which we want to apply element function
row_function is some function that produces an array with a fixed number of columns
  the column count produced by row_function must be identical regardless of input
stack_function is one of V or H

If you're unsure how these work or why we would use them, please review these videos:
https://youtu.be/04jOeiMypXw
https://youtu.be/wEBLT9QfQRw

ncalm

(list1 as list, list2 as list) as list => List.TransformMany(list1, each list2, (x,y) => {x,y})

ncalm

/*
Simple example of FOR JSON PATH

With FOR JSON PATH, we can convert table data to JSON structured text.

By using the . notation, we can create hierarchies of related attributes.
*/
SELECT TOP 5 *
FROM DimCustomer;