'''Learn to Program''' is the '''Contents''' page for topics that are related
to the art of programming in general.


** See Also **

   [Learning Tcl]:   The specifics of [Tcl]

   [Casual Programming - Amateurs, beginners et al]:   

   [BOOK Structure and Interpretation of Computer Programs]:   formerly used as the textbook of the MIT introductory programming class; widely considered a classic text in computer science

   [BOOK Concepts, Techniques, and Models of Computer Programming]:   

   [How to be a Programmer: A Short, Comprehensive, and Personal Summary, Robert L. Read, 2002]:   


** Description **

There are, of course many resources out there in the world, that teach
beginners the art of computer programming.  One of the more well-known is
''[BOOK Structure and Interpretation of Computer Programs%|%The Structure and
Interpretation of Computer Programs]'', but it uses [LISP] rather than Tcl.
Tcl is a fantastic first language for someone interested in getting into
computer programming, and this page teaches Tcl obliquely by teaching the
general art of programming, using Tcl as a resource to illustrate the concepts.


** Values and side effects **

Some commands return useful values, some have side effects, and some do both.


The value of `[[[puts]]` is invariant.  It always returns the empty string, so
it's never useful:

======
set a [puts hello]
======

Therefore, `[[[puts]]` has a side effect, but no useful value.  

`[[[set]]` has a side effect.  It creates a new variable and assigns a value to
it.  `[[[set]]` also returns the value that it assigned to the variable, which
can be useful sometimes.  To set two variables to the same value, one could
write:

======
set b [set a hello]
======

Therefore, `[[[set]]` has a side effect and also has a useful value.

`[[[string length]]` is an example of a command that doesn't have any side
effects but does have a useful value.  It changes nothing in the world of a Tcl
script.  It doesn't create or delete any commands or variables, and it doesn't
write any data to any channels.  However, it returns a value that tells us
something we might want to know:

======
string length hello
======

The last category is commands that have no side effect and no value.  There are
none of these!


** Basics **

   [scope]:   


** [data structure%|%Data Structure] **

   [data structure]:   


** Program Structure **

   [control structure]:   

   [proc]:   

   [Closures%|%closure]:   

   [continuation]:   

   [coroutine]:   

   [Generator]:   

   [iterators%|%iterator]:   


** State **

   [static variables]:   

   [Tcl references in Tcl]:   


** Calculation **


** Processing **

   [parsing]:   

   [serializing%|%serialization]:   


** Design **

   [Model / View / Controller]:   


** Paradigm **

   [Functional Programming]:   


** The Role of Scripting Languages **

   [Why adding Tcl calls to a C/C++ application is a bad idea]:   


** Technique **

   [debugging]:   



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