Phillip Trelford's Array

Microsoft’s C# programming language first appeared in 2000, over 15 years ago, that’s a long time in tech.

Every month or so there’s a “Leaving .Net” articles, the last one I bumped into was “The collapse of the .net ecosystem” from Justin Angel:

"The collapse of the .net ecosystem" @ http://t.co/doKJ712Kqm Wrote this six months ago and didn't want to offend people by publishing it.

— Justin Angel (@JustinAngel) June 1, 2015

The article shows, through a series of charts, the level of interest in C# peaking and then falling.

This is what I’d consider to be the natural continuum of things, where languages have their day, and then slowly decline. In the past C was my primary language, then C++ and so on, why should C# be any different?

Disclaimer: This is not a leaving .Net post, just some of my own research that I thought I’d share, with a focus on the UK as that’s where I live.

Job trends

Indeed.com provides statistics on job placements with specific keywords, lets look at C#:

This chart appears to show job adverts peaking between around 2010 and 2012 and tapering off fairly heavily after that.

Google trends

Google trends lets you track interest over time based on a keyword, here I'm looking at C# in the UK:

On this chart the peak seems to be earlier, around 2009, perhaps the trend can be seen earlier in the UK, but again the decline in interest is clearly visible.

TIOBE

Questions around the validity of TIOBE’s numbers abound, but here it is anyway:

Here the peak appears to be around 2012, although the drop is perhaps less pronounced.

PYPL

Yet another popularity index this time tracking google trends for “C# tutorial” in the UK:

This chart shows uses a logarithmic scale, however what we might surmise, if the numbers are to believed, is that interest in C# appears to fall off a cliff towards the end of 2014.

Stack Overflow

The recent stackoverflow developer survey also shows a significant decline in interest from 44.7% in 2013 to 31.6% in 2015. Developer’s current preferences are also quite revealing:

Where’s everyone gone?

This is only conjecture, but from my experience of .Net oriented developer events over the years in the UK, C# has always had a significant focus on the web and ASP.Net. My suspicion is that with the rise of thick-client JavaScript and mobile, significant numbers of developers have been migrating naturally towards those ecosystems.

Should I panic?

Probably not, there’s still plenty of C# jobs out there for now, and hell, some of the best paid jobs nowadays are for maintaining C++ and even COBOL systems. But if the numbers are anything to go by then we can say that C# interest has peaked.

That said who knows what the future will hold and perhaps like C++ there’ll be a renaissance in the future, although C++’s renaissance never really brought it back to the levels of it’s heady hey days.

Then again perhaps it’s more pragmatic not to dwell too heavily on the past, accept the numbers, and look to a new future. If you’re skills extend beyond one language then I guess you’ve probably got nothing to worry about, otherwise perhaps it’s time to pick up a new language and new paradigms.

And I’ll leave you with a question: Do you think you’ll be using the same programming language in 5 years time?

One of the biggest life lessons I learnt while at school, although I didn’t know it at the time, was from a PE lesson and a game called Rat.

There were only a few rules to Rat: one kid had the ball and could throw at any of the other kids, when you were hit you were out, and the last kid left standing was the rat.

Most of the kids would run and jump around trying to avoid the ball, but would rarely last the distance; the surviving rats tended to push others into the line of fire or better keep their heads down and find a place to hide.

On reflection this seems to be a perfect analogy of the corporate world where “survivors” in a company are typically the ones who keep their head down and try not to draw attention to themselves.

But where’s the fun in that, the real lesson for me was not to get too caught up in the “game”, if you’re hit you can just move on to a new one.

This is a follow up to my last post A Fistful of Dollars, where I looked at test-driven approaches to implementing a money type based on the example running through Kent Beck’s Test-Driven Development by Example book:

In this run I decided as an exercise to skip formal unit testing altogether and just script the functionality for the multi-currency report that Kent is working towards over 100 pages or so of his book:

Unsurprisingly It ended up being relatively quick and easy to implement.

Money type

First off we need a money type with an amount and a currency and support for multiplication and addition:

type Money = private { Amount:decimal; Currency:Currency } 
   with   
   static member ( * ) (lhs:Money,rhs:decimal) = 
      { lhs with Amount=lhs.Amount * rhs }
   static member ( + ) (lhs:Money,rhs:Money) =
      if lhs.Currency <> rhs.Currency then invalidOp "Currency mismatch"
      { lhs with Amount=lhs.Amount + rhs.Amount}
   override money.ToString() = sprintf "%M%s" money.Amount money.Currency
and  Currency = string

In the code above I’ve used an F# record type with operator overloads for multiplication and addition.

Exchange rates

Next we need to be able to do currency conversion based on a rate table:

type RateTable = { To:Currency; From:Map<Currency,decimal> }

let exchangeRate (rates:RateTable) cy =   
   if rates.To = cy then 1.0M else rates.From.[cy]

let convertCurrency (rates:RateTable) money =
   let rate = exchangeRate rates money.Currency
   { Amount=money.Amount / rate; Currency=rates.To }

Here I’ve used a record type for the table and simple functions to look up a rate and perform the conversion.

Report model

Now we need a representation for the input and output, i.e. the user’s positions and the report respectively:

type Report = { Rows:Row list; Total:Money }
and  Row = { Position:Position; Total:Money }
and  Position = { Instrument:string; Shares:int; Price:Money }

Again this is easily described using F# record types

Report generation

Here we need a function that takes the rates and positions and returns a report instance:

let generateReport rates positions =
   let rows =
      [for position in positions ->        
         let total = position.Price * decimal position.Shares
         { Position=position; Total=total } ]
   let total =
      rows
      |> Seq.map (fun row -> convertCurrency rates row.Total)   
      |> Seq.reduce (+)
   { Rows=rows; Total=total }

For the report generation I’ve used a simple projection to generate the rows followed by a map/reduce block to compute the total in the target currency.

Report view

There’s a number of different ways to view a generate the report. At first I looked at WinForms and WPF, which provide built-in data grids, but unfortunately I couldn’t find anything “simple” for showing summary rows.

In the end I plumped for a static HTML view with an embedded table:

let toHtml (report:Report) =
   html [
      head [ title %"Multi-currency report" ]      
      body [
         table [
            "border"%="1"
            "style"%="border-collapse:collapse;"
            "cellpadding"%="8"
            thead [
               tr [th %"Instrument"; th %"Shares"; th %"Price"; th %"Total"] 
            ]
            tbody [
               for row in report.Rows ->
                  let p = row.Position
                  tr [td %p.Instrument; td %p.Shares; td %p.Price; td %row.Total]
            ]
            tfoot [
               tr [td ("colspan"%="3"::"align"%="right"::[strong %"Total"])
                   td %report.Total]
            ]
         ]
      ]
   ]

For the HTML generation I wrote a small internal DSL for defining a page.

If you’re something a little more polished I found these static HTML DSLs on my travels:

• DSL for constructing HTML snippet (using a computation expression)
• FMarkup project (using obj list to avoid noise)

Report data

Finally I can define the inputs and generate the report:

let USD amount = { Amount=amount; Currency="USD" }
let CHF amount = { Amount=amount; Currency="CHF" }

let positions =
   [{Instrument="IBM";      Shares=1000; Price=USD( 25M)}
    {Instrument="Novartis"; Shares= 400; Price=CHF(150M)}]

let inUSD = { To="USD"; From=Map.ofList ["CHF",1.5M] }

let positionsInUSD = generateReport inUSD positions

let report = positionsInUSD |> toHtml |> Html.toString

Which I think is pretty self-explanatory.

Report table

The resultant HTML appears to match the table from the book pretty well:

Summary

I was able to implement the report in small steps using F# interactive to get quick feedback and test out scenarios, with the final result being as expected on first time of running.

Overall I’m pretty happy with the brevity of the implementation. F# made light work of generating the report, and statically generated HTML produced a nice result with minimal effort, a technique I’ll be tempted to repeat in the future.

The full script is available as an F# Snippet.