Right Language for the Job - programming-languages

Using the right language for the job is the key - this is the comment I read in SO and I also belive thats the right thing to do. Because of this we ended up using different languages for different parts of the project - like perl, VBA(Excel Macros), C# etc. We have three to four languages currently in use inside the project. Using the right language for the job has made it immensly more easy to do automate a job, but of late people are complaining that any new person who has to take over the project will have to learn so many different languages to get started. Also it is difficult to find such kind of person. Please note that this is a one to two person working on the project maximum at a given point of time. I would like to know if the method we are following is right or should we converge to single language and try to use it across all the job even though another language might be better suited for it. Your experenece related to this would also help.
Languages used and their purpose:
Perl - Processing large text file(log files)
C# with Silverlight for web based reporting.
LabVIEW for automation
Excel macros for processing data in excel sheets, generating graphs and exporting to powerpoint.

I'd say you are doing it right. Almost all the projects I've ever worked on have used multiple languages, without any problems. I think you may be overestimating the difficulty people have picking up new languages, particularly if they all use the same paradigm. If your project were using Haskell, Smalltalk, C++ and assembler, you might have difficulties, I must admit :-)

Using a variety languages vs maintainability is simply another design decision with cost-vs-benefits trade-offs that, like any design decision, need to considered carefully. While I like using the "absolute best" tool for the task (whatever "absolute best" means), I wouldn't necessarily use it without considering other factors such as:
do we have sufficient skill and experience to implement successfully
will we be able to find the necessary resources to maintain it
do we already use the language/tech in our system
does the increase in complexity to the overall system (e.g. integration issues, the impact on build automation) outweigh the benefits of using the "absolute best" language
is there another language that we already use and have experience in that is usable in lieu of the "absolute best" language
I worked a system with around a dozen engineers that used C++, Java, SQL, TCL, C, shell scripts, and just a touch of Perl. I was proud that we used the "best language" where they made sense, but, in one case, using the "best language" (TCL) was a mistake - not because it was TCL - but rather because we failed to observe the full costs-vs-benefits of the choice:*
we had only 1 engineer deeply familiar with TCL - the original engineer who refused to use anything but TCL for a particular target component - and then that engineer left the project
this target component was the only part of the system to use TCL and it was small relative to the other components in the system
the component could have been also implemented in another language we already used that we had plenty of experience in (C or C++) with some extra effort
the component appeared deceptively simple, but in reality had subtle corner cases that bit us in production (not something we could have known then, but always something to consider as a possibility later)
we had to implement special changes to the nightly build because the TCL compiler (yes, we compiled the TCL code into an executable) wouldn't work unless it could first throw its logo up on the screen - a screen which wasn't available during a cron-initiated automated nightly build. (We resorted to using xvfb to satisfy it.)
when bugs turned up, we had difficult time finding engineers who wanted to work on it
when problems with this component cropped up only after sustained load in the field, we lacked the experience and deep understanding of the TCL execution engine to easily debug it in the field
finally, the maintenance and sustainment team, which is a much smaller team with fewer resources than the main development team, had one more language that they needed training and experience in just to support this relatively small component
Although there were a number of things we could have done to head-off some of the issues we hit down the road (e.g. put more emphasis on getting TCL experience earlier, running better tests to detect the issues earlier, etc), my point is that the overall cost-vs-benefit didn't justify using TCL to code that single component. Again, it was not a mistake to use TCL because it was TCL (TCL is a fine language), but rather it was a mistake because we failed to give full consideration to the cost-vs-benefits.

As a Software Engineer it's your job to learn new languages if you need to. I would say you should go with the right tool for the job.
It's like sweeping the floor with an octopus. Yeah, it gets the job done... kind of... but it's probably not the best tool for the job. You're better off using a mop.
Another option is to create positions geared towards working in specific languages. So you can have a C# developer, a Perl developer, and a VBA developer who will only work with that language. It's a bit more overhead, but it is a workable solution.

Any modern software project of any scope -- even if it's a one-person job -- requires more than one language. For instance, a web project usually requires Javascript, a backend language, and a DB query language (though any of these might be created by the backend language). That said, there's a threshold that is easily reached, and then it would be very hard to find new developers to take over projects. What's the limit? Three languages? Four? Let's say: five is too many, but one would be too few for any reasonably complex project.

Using the right language for the right job is definitely appropriate - I am mainly a web programmer, and I need to know server-side programming (Rails, PHP + others), SQL, Javascript, jQuery, HTML & CSS (not programming languages strictly, but complex things I need to know) - it would be impossible for me to do all of that in a single language or technology.
If you have a team of smart developers, picking up new languages will not be a problem for them. In fact they probably will be eager to do so. Just make sure they are given adequate time (and mentoring) to learn the new language.
Sure, there will be a learning curve to implementing production code if there is a new language to learn, but you will have a stronger team member for it.
If you have developers in your teams who strongly resist learning new languages, unless there is a very good reason (e.g they are justifiably adamant that they are being asked to used a different language when it is not appropriate to do so) - then they are not the sort of developers I'd want in my teams.
And don't bother trying to hire people who know all the languages you use. Hire smart programmers (who probably know at least one language you use) - they should pick up the other languages just fine.

I would be of the opinion, that if I a programmer on my team wanted to introduce a second (or third) language into a project, that there better be VERY VERY good reason to do so; as a project manager I would need to be convinced that the cost of doing so, more than offset the problems. And it would take a lot of convincing.
Splitting up project into multiple languages makes it very expensive to hire the right person(s) to take over that project when it needs maintenance. For small and medium shops it could be a huge obstacle.
Edit: I am not talking about using javascript and c# on the same project, I am talking about using C# for most of the code, F# for a few parts and then VB or C++ for others - there would need to be a compelling reason.
KISS: 'Keep it simple stupid' is a good axiom to follow in most cases.
EDIT: I am not completely opposed to adding languages, but the burden of proof is on the person to who wants to do it. KISS (to me) applies to not only getting the project/product done and shipped, but also must take into account the lifetime maint. and support requirements. Lots of languages come and go, and programmers are attracted to new languages like a moth to a light. Most projects I have worked on, I still oversee and/or support 5 or 10 years later - last thing I want to see is some long forgotten and/or orphaned language responsible for some key part of an application I need to support.

My experience using C++ and Lua was that I wrote more glue than actual operational code and for dubious benefit.

I'd start by saying the issue is whether you are using the right paradigm for the job?
Suppose you know how to do object oriented programming in C#. I don't think the leap to Java is all that great . Although you'd have to familiarize yourself with libraries and syntax, the idea is pretty similar.
If you have procedural parts to your project, such as parsing files and various data transformations, your Perl/Excel Macros seem pretty similar.
But to address your issues, I'd say above all, you'll need clarity in code. Since your staff are using several languages, they won't be familiar with all languages to an equal degree. So make sure of this:
1) Syntactic sugar is explained in comments. Sugars are pretty language specific and may not be obvious to a new reader. For instance, in VBA I seem to remember there are default properties, so that TextBox1 = "Hello" is what you'd write instead of TextBox1.Text = "Hello". This can be confusing. Also, things like LINQ statements can have un-obvious meanings. So make sure people have comments to read.
2) Where two components from different languages have to work together, make excruciatingly specific details about how that happens. For instance, I once had to write a C component to be called from Excel VBA. There's quote a few steps and potential errors in doing this, especially as far as compiler flags. Make sure both sides know how their side of the interaction occurs.
Finally, as far as hiring people goes, I think you have to find people who aren't married to a specific language. To put it vaguely, hire an intelligent person who sees business issues, not code. He'll learn the lingo soon enough.

Related

Best language to manipulate sound?

I would like to make an "simple" program that after i clap the hands would do an certain event like open a browser. However i want do other things after this, so the program must be able to evolve.
Which programing languague should i choose in order to do this?
I know vb, python, c, c++, learning java(isnt going very well).
Thanks.
To be honest, I just don't believe that you 'know' vb, python, c, and c++. Because if you did - you'd know that all you have to do to is google the problem, and you'd find a solution for multiple different languages.
I think instead of trying to jump into a 'clap detection app', a better idea would be to start slowly and actually MASTER (or at least start trying to master) one language. A jack of all trades is a master of none - and this is especially true in beginning programming. Just dive into one of the languages you 'know', I'd suggest Python due to its general user-friendliness and diverse supporting libraries. Just keep learning and eventually you'll be able to do almost anything!
I would like to give a simple, non-opinion based answer. A programming language serves two purposes:
"it provides a vehicle for the programmer to specify actions to be executed,
it provides a set of concepts for the programmer to use when thinking about what can be done."
(Bjarne Stroustrup: "C++ programming language, 1.3.2.)
Your problem is not simple at all - clap detection is not a trivial thing to do: it involves real-time detection of a time characteristic, spectral characteristic and possibly a visual gesture (not to be confused with a similar sound from a different source). Take into account that a clap from the same person in different spaces also sounds differently. Take into account possible dynamic variations.
Only by learning languages in depth you'll be able to get familiar with language specific concepts for the programmer to use when thinking about what can be done, as well as with specifying actions to be executed for any particular language.
Also, when dealing with sound, you need a basic knowledge of acoustics.
As a rule of thumb, almost all serious real-time audio processing code is written in languages which are mature, small and can make fast runtime executables.

Does this language have its niche | future?

I am working on a new language, targeted for web development, embeding into applications, distributed applications, high-reliability software (but this is for distant future).
Also, it's target to reduce development expenses in long term - more time to write safer code and less support later. And finally, it enforces many things that real teams have to enforce - like one crossplatform IDE, one codestyle, one web framework.
In short, the key syntax/language features are:
Open source, non-restrictive licensing. Surely crossplatform.
Tastes like C++ but simpler, Pythonic syntax with strict & static type checking. Easier to learn, no multiple inheritance and other things which nobody know anyway :-)
LLVM bytecode/compilation backend gives near-C speed.
Is has both garbage collection & explicit object destruction.
Real OS threads, native support of multicore computers. Multithreading is part of language, not a library.
Types have the same width on any platform. int(32), long(64) e.t.c
Built in post and preconditions, asserts, tiny unit tests. You write a method - you can write all these things in 1 place, so you have related things in one place. If you worry that your class sourcecode will be bloated with this - it's IDEs work to hide what you don't need now.
Java-like exception handling (i.e. you have to handle all exceptions)
I guess I'll leave web & cluster features for now...
What you think? Are there any existing similar languages which I missed?
To summarize: You language has no real selling points. It just does what a dozen other languages already did, with syntax and semantics just slightly off, depending on where the programmer comes from. This may be a good thing, as it makes the language easier to adapt, but you also have to convince people to trouble to switch. All this stuff has to be built and debugged and documented again, tools have to be programmed, people have to learn it and convince their pointy-haired bosses to use it, etc. "So it's language X with a few features from Y and nicer syntax? But it won't make my application's code 15% shorter and cleaner, it won't free me from boilerplate X, etc - and it won't work with my IDE." The last one is important. Tools matter. If there are no good tools for a language, few people will shy away, rightfully so.
And finally, it enforces many things that real teams have to enforce - like one crossplatform IDE, one codestyle, one web framework.
Sounds like a downside! How does the language "enforce one X"? How do you convince programmers this coding style is the one true style? Why shouldn't somebody go and replace the dog slow, hardly maintained, severly limited IDE you "enforce" with something better? How could one web framework possibly fit all applications? Programmers rarely like to be forced into X, and they are sometimes right.
Also, you language will have to talk to others. So you have ready-made standard solutions for multithreading and web development in mind? Maybe you should start with a FFI instead. Python can use extensions written in C or C++, use dynamic libraries through ctypes, and with Cython it's amazingly simple to wrap any given C library with a Python interface. Do you have any idea how many important libraries are written in C? Unless your language can use these, people can hardly get (real-world) stuff done with it. Just think of GUI. Most mayor GUI toolkits are C or C++. And Java has hundreds of libraries (the other JVM languages profit much from Java interop) for many many purposes.
Finally, on performance: LLVM can give you native code generation, which is a huge plus (performance-wise, but also because the result is standalone), but the LLVM optimizers are limited, too. Don't expect it to beat C. Especially not hand-tuned C compiled via icc on Intel CPUs ;)
"Are there any existing similar
languages which I missed?"
D? Compared to your features:
The compiler has a dual license - GPL and Artistic
See example code here.
LDC targets LLVM. Support for D version 2 is under development.
Built-in garbage collection or explicit memory management.
core.thread
Types
Unit tests / Pre and Post Contracts
try/catch/finally exception handling plus scope guarantees
Responding to a few of your points individually (I've omitted what I consider either unimportant or good):
targeted for web development
Most people use php. Not because it's the best language available, that's for sure.
embeding into applications
Lua.
distributed applications, high-reliability software (but this is for distant future).
Have you carefully studied Erlang, both its design and its reference implementation?
it enforces many things that real teams have to enforce - like one crossplatform IDE, one codestyle, one web framework.
If your language becomes successful, people will make other IDEs, other code styles, other web frameworks.
Multithreading is part of language, not a library.
Really good languages for multithreading forbid side effects inside threads. Yes, in practice that pretty much means Erlang only.
Types have the same width on any platform. int(32), long(64) e.t.c
Sigh... There's only one reasonable width for integers outside of machine-level languages like C: infinite.
Designing your own language will undoubtedly teach you someting. But designing a good language is like designing a good cryptosystem: lots of amateurs try, but it takes an expert to do it well.
I suggest you read some of Norman Ramsey's answers here on programming language design, starting with this thread.
Given your interest in distributed applications, knowing Erlang is a must. As for sequential programming, the minimum is one imperative language and one functional language (ideally both Lisp/Scheme and Haskell, but F# is a good start). I also recommend knowing at least one high-level language that doesn't have objects, just so you understand that not having objects can often make the programmer's life easier (because objects are complex).
As for what could drive other people to learn your language... Good tools/libraries/frameworks can't hurt (FORTRAN, php), and a big company setting the example can't hurt (Java, C#). Good design doesn't seem to be much of a factor (a ha-ha-only-serious joke has it that what makes a language successful is using {braces} to delimit blocks: C, C++, Java, C#, php)...
What you've given us is a list of features, with no coherent philosophy, or explanation as to how they will work together. None of the features are unique. At best, you're offering incremental improvements over what's already there. I'd expect there's already languages kicking around with what you've said, it's just that they're still fairly obscure, because they didn't make it.
Languages have inertia. People have to learn new languages, and sometimes new tools. They need incentive to do so, and 20% improvement in a few features doesn't cut it.
What you need, at a minimum, is a killer app and a form of elevator pitch. (The "elevator pitch" is what you tell the higher-ups about your project when you're in the elevator with them, in current US business parlance.) You need to have your language be obviously worth learning for some purpose, and you need to be able to tell people why it's worth learning before they think "just another language by somebody who wanted to write a language" and go away.
You need to form a language community. That community needs to have some localization at first: people who work in X big company, people who want to do Y, whatever. Decide on what that community is likely to be, and come up with one big reason to switch and some reasons to believe that your language can deliver what it promises.
No.
Every buzzword you have included in your feature list is an enormous amount of work to be spec'd, implemented, documented, and tested.
How many people will be actively developing the language? I guess the web is full of failed programming language projects. (Same is true for non-mainstream OSes)
Have a look at what .Net/Visual Studio or Java/Eclipse have accomplished. That's 1000s of years of specification, development, tests, documentation, feedback, bug fixes, service packs.
During my last job I heard about somebody who wrote his own programming framework, because it was "better". The resulting program code (both in the framework and in the applications) is certainly unmaintainable once the original programmer quits, or is "hit by a bus", as the saying goes.
As the list sounds like Java++ or Mono++, you'd probably be more successful in engaging in an existing project, even if it won't have your name tag on it.
Perhaps you missed one key term. Performance.
In any case, unless this new language has some really out-of-this-world features(ex: 100% increase in performance over other web development languages), I think it will be yet another fish in the pond.
Currently I'm responsible for maintaining a framework developed/owned by my company. It's a nightmare. Unless there is a mainstream community, working on this full time, it's really an elephant. I do not appreciate my company's decision to develop its own framework(because it's supposed to be "faster") day 'n night.
The language tastes good in my opinion, I don't want use java for a simple website but I would like to have types and things like that. ASP .NET is a problem because of licensing and I can't afford those licenses for a single website... Also features looks good
Remember a lot of operator overloading: I think is the biggest thing that PHP is actually missing. It allows classes to behave much more like basic types :)
When you have something to test I'll love to help you with it! Thanks
Well, if you have to reinvent the wheel, you can go for it :)
I am not going to give you any examples of languages or language features, but I will give you one advice instead:
Supporting framework is what is the most important thing. People will tend to love it or hate it, depending on how easy is to write good code that get job done. Therefore, please do usability test before releasing it. I mean ask several people how they will do certain task and create API accordingly. Then test beta API on other coders and listen carefully to their comments.
Regards and good luck :)
There's always space for another programming language. Apart from getting the design right, I think the biggest problem is coming across as just another wannabe language. So you may want to look at your marketing, you need a big sponsor who can integrate your language into their products, or you need to generate a buzz around it, easiest way is astroturfing. Good luck.
http://en.wikipedia.org/wiki/List_of_programming_languages
NB the names G and G++ aren't taken. Oh and watch out for the patent trolls.
Edit
Oops G / G++ are taken... still there are plenty more letters left.
This sounds more like a "systems" language rather than a "web development language". The major languages in this category (other than C++/C) are D and Go.
My advice to you would be to not start from scratch but examine the possibility of creating tools or libraries for those languages, and seeing just how far you can push them.

Resources for learning a new language quickly?

The title may seem slightly self-contradictory, and I accept that you can't really learn a language quickly. However, an experienced programmer that already has knowledge of a few languagues and different styles (functional, OO, imperative etc.) often wants to get started quickly. I've seen a few websites doing effective "translations" in the form of "just show me syntax equivalence". I can't remember the sites now, but for related languages (e.g. Perl/PHP) it's quite common.
Is there a better resource that covers more languages? Is there a resource that covers idioms as well as syntax? I think this would be incredibly useful for doing small amounts of work on existing code bases where you are not familiar with the language. Looking at the existing code, as we know, is not always a good indicator of quality. Likewise, for "learn by doing" weekend project I always have the urge to write reasonably idiomatic, clean code from the start. Such a resource could also link to known good example projects of varying sizes for those that prefer to learn by reading. Reading a well-written medium sized code base can also be much more practical when access to development environments might be limited.
I think it's possible to find tutorials and summaries for individual languages that provide some of this functionality in disparate web locations but I'm hoping there is a good, centralised, comparative place that the busy programmer can turn to.
You generally have two main things to overcome:
Syntax
Reference
Syntax you can pick up fairly quickly with a language tutorial and a stack of samplecode.
Reference (library/API calls) you need to find a proper guide to; perhaps the language reference, or perhaps google...
With those two in place, following a walkthrough (to get you used to using the development environment) will have you pretty much ready - you'll be able to look up what you want to say (reference), and know how to say it (syntax).
This, of course, applies principally to procedural/oop languages; languages that require a paradigm switch (ML/Haskell) you should go to lectures for ;)
(and for the weirder moments, there's SO!)
In the past my favour was "learning by doing". So e.g. I know a little bit of C++ and a lot of C#.Net but I must write a FTP Tool in Python.
So I sit for an hour and so the syntax differences by a tutorial, than I develop the form itself and look at the generated code. Then I search a open source Python FTP Client and get pieces of code (Not copy and paste, write it self to see, feel and remember the code!)
After a few hours I get it.
So: The mix is the best. A book, a piece of good code, the willing to learn and a free night with much coffee.
At the risk of sounding cheesy, I would start with the language's website tutorial and/or FAQ, followed by asking more specific questions here. SO is my centralized location for programming knowledge.
I remember when I learned Perl. I was asked to modify some Perl code at work and I'd never seen the language before. I had experience with several other languages, however, so it wasn't hard to figure out the syntax with the online Perl docs in one window and the code in another, side-by-side. I don't know that solely reading existing code is necessarily the best way to learn. In my case, I didn't know Perl but I could tell that the person who originally wrote the code didn't know Perl either. I'm not sure I could've distinguished between good Perl and really confusing Perl. It would've been nice to be able to ask questions here at the time.
Language isn't important. What is important is learning your ways around designing algorithms and the proper application of design patterns. Focus on the technique, not the language that implements a certain technique. Once you understand the proper development techniques, any programming language will just become real easy, no matter how obscure they are...
When you put a focus on a language, you're restricting your own knowledge.
http://devcheatsheet.com/ seems to be a step in the right direction: it aggregates cheat sheets/quick references and they are (somewhat) manually reviewed. It's also wide-ranging. It still comes up short a bit in terms of "idiomatic" quick reference: for example, the page on Ruby doesn't mention yield.
Rosetta Code appears to be an excellent resource that includes hints on coding idiomatically and moves from simple (like for-loops) to things like drawing. I haven't checked out how comprehensive it is, but there are a large number of languages and tasks listed. The drawbacks re: original question are:
Some of the linking is not accurate
(navigating Python->ForLoop will
take you to the top of the ForLoop
page, not the Python section). It's a
wiki, this can be improved.
Ideally you could "slice" the wiki
however you chose to see e.g. the top
20 tasks for two languages
side-by-side.
http://hyperpolyglot.org/ seems to be an almost perfect match for what I was looking for. The quality is not always there, or idiom can be lacking, but it has the same intention and is pretty comprehensive.

Company standards: C#.NET vs VB.NET vs. whatever.NET

Just a question that came up from time to time at my old job when we were considering fleshing out our development staff with additional bodies. Does it really matter, if you are a .NET development house, if your developers all code in one language vs another.
I probably started out like alot of the 4million other folks there with Visual Basic way back when, and then migrated to VB.NET. Another developer we had at the time came from a C background and migrated over to C#.NET. Basically he was able to code very quickly in his native language and I was able to do so in mine and since our projects did not really overlap there was no issue until our boss basically said we need to switch to C#... for no other reason than standardization.
So I guess the 'subjective' part of the question is, is it better to sacrifice productivity for consistency? Now I should quantify this in saying we were a SMALL shop, less than 5 developers and given how most of our project plans were done on cocktail napkins its not like we were going for 6-Sigma anytime soon so it was not like 'standards' were a hard and fast rule.
Thanks.
C# is definitely becoming the preferred avenue for Microsoft and it would make sense to choose a language that all developers to use simply based on the fact that if developers move between tasks, having the projects in a uniform language (not to mention coding conventions) will make the maintenance on those projects much easier for everyone involved.
If it helps, I recently wrote an article on my blog looking back at my decision to standardize our development shop on VB.NET over C# and how well my various assumptions have held up and things hindsight has shown me.
Here's a link: "A Manager’s Retrospective on the C# versus VB.NET decision"
As to whether you should standardize the whole shop on one language. I'd say there are definite benefits. The most obvious one is that switching back and forth when you work on different projects is going to incur some mental overhead to re-acclimate yourself each time. Granted, it is going to be less if you have to do it frequently, but to justify the extra complexity there would have to be some offsetting benefit.
Ultimately my advice is to standardize on one or the other based on the following criteria:
(1) If you have a large VB code-base there is a good argument for standardizing on VB.NET.
(2) If everything else is equal, I'd lean towards C# for a number of reasons mentioned in the above article.
(3) Carefully take into account your current team's preferences and the general consensus among developers in your market that you would try to recruit. Language choice is a big deal for morale and hiring.
I think it makes sense to pick one and get everyone on it. The sacrifice in productivity will be brief, competent developers will migrate quickly.
Some advantages:
your last VB developer and the team get downsized...uh oh.
one of the developers quits and you have to take over their code
etc.
I'd say go for whatever works. VB.NET and C# use all the same underlying framework so you should be able to read each others code and with a little googling you should be able to modify it too.
I'd say go for productivity.. ultimately is the customer going to care if it's written in VB.NET or C#?? But saying that you have to think about maintanability.
So I guess the 'subjective' part of
the question is, is it better to
sacrifice productivity for
consistency?
Of course not. What good is consistency, by itself? Ultimately the goal of consistency is productivity. With that in mind, I would suggest that, long term, having everyone code in one language would be the best way to go...in general over the long haul, a lot more time is spent modifying and maintaining code than in writing it, and I would think that having people spend the ramp up time once would be better than having to switch back and forth all the time.
our boss basically said we need to
switch to C#... for no other reason
than standardization. (...) So I guess
the 'subjective' part of the question
is, is it better to sacrifice
productivity for consistency?
Of course not. The only question is what value this 'consistency' has in terms of future productivity, because productivity is all that matters. 'Consistency' by itself is not a business value. It may only help you to achieve more productivity in the future.
Several factors must be balanced:
(+) Tomorrow people will have to maintain only one language, the most popular .Net language: C#. (See Note 1)
(-) Today you must learn C#, which is a cost for your company, unless you do it for free in your weekends. Of course this is a (-) in terms of cost. Learning C# is good by itself, it just has a cost.
(-) Today after learning C#, you or someone else must switch one project from Visual Basic .Net to C#. That has a cost, depending on the LOC count of the project. Also, errors might be introduced, so you need to rerun your unit tests, go over all the failures and work them out. Also, you need to repeat some integration testing, to guarantee that everything works well.
You can't tell what the outcome of the balance is with this information. But you don't have to tell, anyway, since your boss presumably has better information and has already taken the decision. All that you need to do is to actually do it.
Note 1: However, this reasoning is dangerously close to "the world would be a better place if VB.NET didn't exist", which may be too strong a statement. VB.NET, or a mix of both languages, might be a good option in some scenarios.
We're still a mixed language group where I work; however, mixed with a purpose. Nearly all hardware related projects are done in C++ (not assembly, I know :() and all nearly all windows applications are done in C#.
Considering C# popularity and ease, I'd say it's in a company's interest to move to it for when they get new, greener employees.
How do you see yourself as shop?
VB.NET is strong in markets that directly lean on Office, maybe client apps too, while C# is particularly strong in serverside and larger applications.
Maybe it is not about following your or his choice, but make a choice to align with the nature of the shop.
It is important to stick to a singular language choice, if possible. Obviously, if you are writing unmanaged C++, or have some other similar scenario, there would be notable exceptions. Many people have hit on the efficiency of homogeneous language choices, once you have ramped up. Most of the developers I know will run into an efficiency issue when switching languages, even if they know it inside and out. After coding in C# for a couple of months, if I have to go back to VB.NET to maintain something, there is a good day where I have to consciously think about things that are normally automatic. They are simple things, like using vs. Imports, type conversion, etc. It isn't that you forget how it works, but that your mind wants to do something the way you have been doing it for an extended period. A lot like the old parlor trick of pushing your arms out against a door frame for a minute and then resting them at your side. They want to go back up, because that is the signal that your brain is used to sending.
Another very important takeaway, is that this efficiency factor is important in code reviews, as well. If you are working in VB.NET and have to review C#, you are going to have the same stumbling blocks. Sure, you understand the code, but your rate or accuracy in analyzing the code will not be the same as it would be if it was in the same language you are currently using.
There are some additional minor points. Some tooling is geared towards one language over another. For example, Resharper works for both VB.NET and C#, but it provides a larger set of refactorings if you are using C#. Also, if someone in your organization maintains a company coding standard, it makes changes to those standards half as complex, if only a single language needs to be addressed.
I think this also goes a long with coding style standards. Is there really a reason why a development team chooses to go with 3 spaces for tabs rather than 4? Not really there is no technical or business advantage to this decision other than uniformity and making everyone's code look the same so when I switch between files my brain doesn't have to adjust to the new formatting.
Same thing applies here with the uniformity for C# and VB.net. There is no technical or business advantage for taking one over the other (NOTE: I'm sure if you looked hard enough you could find something really obscure). But having everyone's code uniform helps when moving from project to project so people don't have to switch gears from thinking in C# to thinking in VB.net.
One of the advantages of using the .Net platform for development is the fact that you have the ability to develop in the language that is best able to express you solution to the problem at hand.
An arbitrary rule IMO should not prevent you from using F# or a DLR language when those languages would be a more natural fit than an imperative language like C# or VB.Net.
It's a harder decision to make with VB.Net vs. C# because the languages are so similar but If you need to do a lot of work with XML then VB.Net's XML literals may help make the code clearer, conversely C#s terse syntax and support for anonymous methods may make your intent clearer.

Why do you or do you not implement using polyglot solutions?

Polyglot, or multiple language, solutions allow you to apply languages to problems which they are best suited for. Yet, at least in my experience, software shops tend to want to apply a "super" language to all aspects of the problem they are trying to solve. Sticking with that language come "hell or high water" even if another language is available which solves the problem simply and naturally. Why do you or do you not implement using polyglot solutions?
I almost always advocate more than 1 language in a solution space (actually, more than 2 since SQL is part of so many projects). Even if the client likes a language with explicit typing and a large pool of talent, I advocate the use of scripting languages for administrative, testing, data scrubbing, etc.
The advantages of many-language boil down to "right tool for the job."
There are legitimate disadvantages, though:
Harder to have collective code ownership (not everyone is versed in all languages)
Integration problems (diminished in managed platforms)
Increased runtime overhead from infrastructure libraries (this is often significant)
Increased tooling costs (IDEs, analysis tools, etc.)
Cognitive "bumps" when switching from one to another. This is a double-edged sword: for those well-versed, different paradigms are complementary and when a problem arises in one there is often a "but in X I would solve this with Z!" and problems are solved rapidly. However, for those who don't quite grok the paradigms, there can be a real slow-down when trying to comprehend "What is this?"
I also think it should be said that if you're going to go with many languages, in my opinion you should go for languages with significantly different approaches. I don't think you gain much in terms of problem-solving by having, say, both C# and VB on a project. I think in addition to your mainstream language, you want to have a scripting language (high productivity for smaller and one-off tasks) and a language with a seriously different cognitive style (Haskell, Prolog, Lisp, etc.).
I've been lucky to work in small projects with the possibility to suggest a suitable language for my task. For example C as a low-level language, extending Lua for the high-level/prototyping has served very well, getting up to speed quickly on a new embedded platform. I'd always prefer two languages for any bigger project, one domain-specific fit to that particular project. It adds a lot of expressiveness for quickly trying out new features.
However probably this serves you best for agile development methods, whereas for a more traditional project the first hurdle to overcome would be choosing which language to use, when scripting languages tend to immediately seem "newcomers" with less marketing push or "seriousness" in their image.
The biggest issue with polyglot solutions is that the more languages involved, the harder it is to find programmers with the proper skill set. Particularly if any of the languages are even slightly esoteric, or hail from entirely different schools of design (e.g. - functional vs procedural vs object oriented). Yes, any good programmer should be able to learn what they need, but management often wants someone who can "hit the ground running", no matter how unrealistic that is.
Other reasons include code reuse, increased complexity interfacing between the different languages, and the inevitable turf wars over which language a particular bit of code should belong in.
All of that said, realize that many systems are polyglot by design -- anything using databases will have SQL in addition to some other language. And there's often scripting involved as well, either for actual code or for the build system.
Pretty much all of my professional programming experience has been in the above category. Generally there's a core language (C or C++), SQL of varying degrees, shell scripting, and possibly some perl or python code on the periphery.
My employer's attitude has always been to use what works.
This has meant that when we found some useful Perl modules (like the one that implements "Benford's Law", Statistics::Benford), I had to learn how to use ActiveState's PDK.
When we decided to add interval maths to our project, I had to learn Ada and how to use both GNAT and ObjectAda.
When a high-speed string library was requested, I had to relearn assembler and get used to MASM32 and WinAsm.
When we wanted to have a COM DLL of libiconv (based on Delphi Inspiration's code), I got reacquainted with Delphi.
When we wanted to use Dr. Bill Poser's libuninum, I had to relearn C, and how to use Visual C++ 6's IDE.
We still prototype things in VB6 and VBScript, because they're good at it.
Maybe sometime down the line I'll end up doing stuff in Forth, or Eiffel, or D, or, heaven help me, Haskell (I don't have anything against the language per se, it's just a very different paradigm.)
One issue that I've run into is that Visual Studio doesn't allow multiple languages to be mixed in a single project, forcing you to abstract things out into separate DLLs for each language, which isn't necessarily ideal.
I suspect the main reason, however, is the perception that switching back and forth between many different languages leads to programmer inefficiency. There is some truth to this, I switch constantly between JavaScript, C#, VBScript, and VB.NET and there is a bit of lost time as I switch from one language to another, as I mix my syntax a bit.
Still, there is definitely room for more "polyglot" solutions particularly that extend beyond using JavaScript and whatever back-end programming language.
Well, all the web is polyglot now with Java/PHP/Ruby in the back and JavaScript in the front...
Other examples that come to mind -- a flexible complex system written in a low level language (C or C++) with an embedded high level language (Python, Lua, Scheme) to provide customization and scripting interface. Microsoft Office and VBA, Blender and Python.
A project which can be done in a scripting language such as Python with performance critical or OS-dependent pieces done in C.
Both JVM and CLR are getting lots of new interesting scripting languages compatible. Java + Groovy, C# + IRonPython etc.

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