chriskuech / functional Goto Github PK

The Merge-Object function pipes $input to Reduce-Object, but the $input variable is not created anywhere. It looks like it should be piping the $Object parameter of the Merge-Object function.

Consequently, when I ran the Merge-Object function, I was getting no output, because it is always sending $null to Reduce-Object.

I want to use the functional "reduce" function to calculate things, such as the factorial of a number. e.g. The factorial of 5 is 5x4x3x2x1 = 120. In Ruby I can do it with something like:

# factorial1.rb

(1..5).reduce{|accumulator,element| accumulator*element}

In Powershell I would do something like:

# factorial.ps
# ------ Install this library before using the "reduce" function
# Install-Module -Name functional

1..5 | reduce {$a*$b}  

In both languages, the answer is 120, and the accumulator is assumed to be an integer, with an
initial value of the first element in the range.

If I redefined the factorial to have an initial value of 10, in Ruby I
would code it as

# factorial2.rb
# (1..5).reduce    {|accumulator,element| accumulator*element} #uninitialized accumulator
  (1..5).reduce(10){|accumulator,element| accumulator*element}

This yields the expected answer of 1200.

QUESTION 1: How does one initialize a "reduce" accumulator in Powershell?

In the next scenario, I want to generate a list of factorials. If
I were to code it in Ruby, I could initialize the reduce accumulator
with [1] (because 0! is 1), resulting in the following code:

# factorial.rb
# (1..5).reduce     {|accumulator,element| accumulator*element}  #uninitialized accumulator
  (1..5).reduce([1]){|accumulator,element| accumulator << accumulator[-1]*element}

The output looks something like

   => [1, 1, 2, 6, 24, 120]

QUESTION 2: How does one use an expandible array to initialize the accumulator for the
Powershell "reduce" function of the "functional" module?

Scoping rules are explained the opposite of how they actually work.

If Test-All is true, then Test-Any should automatically be true too

Code to Reproduce

@() | functional\Test-All
@() | functional\Test-Any

Output

@() | functional\Test-All
True
@() | functional\Test-Any
False

Merge-Object @{a = @{b = 1}} @{a = @{c = 2}} -Strategy Fail

Merge-Object : A positional parameter cannot be found that accepts argument 'System.Collections.Hashtable'.
At line:1 char:1
+ Merge-Object @{a = @{b = 1}} @{a = @{c = 2}} -Strategy Fail
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [Merge-Object], ParameterBindingException
    + FullyQualifiedErrorId : PositionalParameterNotFound,Merge-Object

I found reading the pester tests helpful.

How would you do compare-object?

It would be really helpful to generalize the "Reduce-Object", adding also an initial value inline to be used as accumulator.
I'm not quite sure on how would it be the idiomatic way to go with Powershell.

Comparing Ordered-dictionaries using recursiveEquality does not work.