When comparing Tcl vs Erlang, the Slant community recommends Tcl for most people. In the question“What is the best programming language to learn first?” Tcl is ranked 31st while Erlang is ranked 44th. The most important reason people chose Tcl is:
Unlike *sh Tcl has a rich standard library.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Standard library
Unlike *sh Tcl has a rich standard library.
Pro Sane quoting rules
Unlike in sh you don't need to quote your variable substitutions ('"$1"').
Expanding of arguments occurs mostly explicit and if yet expected in-place (e. g. using eval
or subst
) it follows strict and well clear rules.
So exec test $argv
would execute test with single argument.
And appending {*} before $argv
would execute test with all arguments (list expansion).
Pro Cross-platform
With a little care you can have the same script work on Linux, *BSD, OS X and Windows.
Pro Widely available
You can expect a reasonably recent version of Tcl to either installed or available in the repositories of any popular open source *nix.
Pro Everything is a string
Tcl can operate at the same level of abstraction as the POSIX shell, which makes it easier to manipulate the output of other programs.
Pro Tk and Expect
Pro Standalone packages
Tcl enables easy deployment through self-contained binaries known as starpacks.
Pro Rich scripting capabilities on a single line
Want to run something 5 times? Here you go: set i 0; time { puts done-[incr i] } 5
If you need real conditional cycle? Not a problem: for {set ready 0; set i 1} {$i <= 100 && !$ready} {incr i} { if {[exec do-some-thing] eq "ready" } {set ready 1} }
Want to measure performance of something or repeat it max 300 times and not longer than 1 seconds? Very simple: timerate { after 20 } 1000 300
How about notifying yourself when some http-server is back online? Sure thing: while {[catch { close [socket localhost 80] }]} { after 1000 }; puts "\7\7\7ONLINE!"
And you can do it also fully asynchronously using events etc.
Pro Built from the ground up with concurrency and distributed computing in mind
Erlang has strong roots with the telecom industry in which concurrent processes are normal. It's designed to be concurrent, to be used for distributed computing and to be scalable.
Pro Fault-tolerant
Fault tolerance means that a system has the property to continue operating even though one or more components have failed.
For Erlang systems, this means that the system is kept running even if for example a user has to drop a phone call rather than forcing everyone else to do so.
In order to achieve this, Erlang's VM gives you:
- Knowledge of when a process died and why that happened
- The ability to force processes to die together if they depend on each other and if one of them has a fault.
- A logger that logs every uncaught exception
- Nodes that can be monitored so that you find out when they go down
- The ability to restart failed processes (or groups of them)
Pro Upgrade code without stopping the system
In a real-time system it may not be possible to stop the system in order to implement code upgrades. For these cases Erlang gives you dynamic code upgrade support for free when using OTP. The mechanism is very easy to understand and works as follows:
- Start the app
- Edit the code
- Recompile
That's all that is needed, the app updates with the new code while it's still running and tests are run automatically.
Pro Great for writing distributed applications
Erlang is made to be parallel and distributed. Because it's very easy to write code that uses multiple processor cores, it's also very easy to write applications that span multiple servers.
Pro Battle proven
Erlang has been used in production for more than 20 years now. During that time it has proven itself over and over again that works great in both small startups and large-scale enterprise systems.
Erlang has been used extensively by Ericsson themselves. For example, the AXD301 ATM, which is one of Ericsson's flagships is probably the largest Erlang project ever with more than 1.1 million lines of Erlang code.
Pro Light processes
Erlang's processes have very little overhead (about 500 bytes per process). This means that a huge amount of processes can be created, even on older machines.
Pro Consistency across platforms
Erlang's processes run in a complete independent way from the OS (they aren't managed by the OS scheduler neither). This means that programs written in Erlang will run exactly the same way regardless of the operating system or platform.
Cons
Con Eccentric syntax
Erlang's syntax may feel very strange to 99% of programmers who have never used it. This is because it does not share any similarities or common syntax definitions that are found in all the other languages that are used today.
Con Useful in only one niche
Erlang is not really a general purpose language. It has a very special and well-defined niche where it towers above everything else. It's specialized in scalability and in distributed applications. Which is not necessarily a bad thing per se, but it still lacks and falls behind other languages when it needs to do things outside it's niche.