It augments the current unknown code, at the top, with a handler for. So, put the following source code in a test.tcl file. Procedures are just like functions we use in any other programming language such as C, Java, Python, etc. Genres Programming. Assume John Smith borrows "The Tempest". Just say "Hello, World!". In the algebra introduced here, with a variable "a", no further simplification was so far possible. Just choose how to implement instance variables: The task of frameworks, be they written in Tcl or C, is just to hide away gorey details of the implementation in other words, sugar it:) On the other hand, one understands a clockwork best when it's outside the clock, and all parts are visible so to get a good understanding of OO, it might be most instructive to look at a simple implementation. It was then ported to Windows, DOS, OS/2, and Mac OSX. For Tcl, there have been several OO extensions/frameworks (incr Tcl, XOTcl, stooop, Snit to name a few) in different flavors, but none can be considered as standard followed by a majority of users. In Tcl, the two ways of reading a file are a good example: The second construct may be less efficient, but is robust for gigabyte-sized files. In TOOT, the values of objects are represented as a list of length 3: the class name (so much for "runtime type information":-), a "|" as separator and indicator, and the values of the object, e.g. For instance, if you would like to simplify the for loop, for the typical simple cases so you can write instead. Tcl/Tk for Programmers: With Solved Exercises that Work with Unix and Windows | Wiley Wiley : Individuals Shop Books Search By Subject Browse Textbooks Courseware WileyPLUS Knewton Alta zyBooks Test Prep (View All) CPA Review Courses CFA Program Courses CMA Exam Courses CMT Review Courses Brands And Imprints (View All) Dummies JK Lasser Just for comparison, here's how it looks in J: Boolean functions, in which arguments and result are in the domain {true, false}, or {1, 0} as expr has it, and operators are e.g. #-- This "functional form" is mostly called map in more recent FP: #-- Prefix multiplication comes as a special case of this: "if {\[$condition \$x\]} {$function \$x} else", #-- Testing, with K in another role as Konstant function:). Every language has its own way of doing things. Here, pushing has to be done by dedicated code because a previous instance would have to be removed: The first element is the least recently, the last the most recently used. (in a fantasy OO style): which, I admit, reads definitely better. This chapter provides an overview of the Tcl syntax, data structures, and enough commands to develop applications. Develop fluency in 67 programming languages ", as it might also stand for factorial and see the shortest function body I ever wrote:^): Without big mention, functions implemented by recursion have a pattern for which func is well suited (see fac and gcd above). Of course this is no real assembler. 100% free. The idea in the paper I read is to use them as names of very simple functions: Glory be to the 11 rules of man Tcl that this is already a crude though sufficient reimplementation: The bracketed expr command is evaluated first, returning 0 or 1 as result of the comparison. is a popular function with super-exponential growth. Tcl (Tool Command Language) is a very powerful but easy to learn dynamic programming language, suitable for a very wide range of uses, including web and desktop applications, networking, administration, testing and many more. The source code is compiled into bytecode, which is later interpreted by the Tcl interpreter. Newbie Tcl/Tk exercises. . This makes sense, even in Tcl, where one might implement them as. An obvious string representation of a rational is of course "n/d". If composite functions like 'fork' are arguments to o*, we'd better let unknown know that we want auto-expansion of first word: Also, we need a numeric sort that's good for integers as well as reals ("Def" serves for all kinds of aliases, not just combinations of functions): As this file gets tacitly sourced, I am pretty confident that I've reached my goal for this weekend even though my median doesn't remotely look like the J version: it is as "wordy" as Tcl usually is. The process of creating a simple database consists only of setting an initial value for the ID: Let's consider a library application for an example. So I tried with another a^2+b^2=c^2 set, and HEUREKA! In Europe and elsewhere, the most widely used paper format is called A4. In both cond and body you may use the variable args that holds the problem command unknown was invoked with. The first formats a matrix (a list of lists to Tcl) with newlines and aligned columns for better display: Short again, and slightly cryptic, as is the "outer product" routine, which takes a function f and two vectors, and produces a matrix where f was applied to every pair of a x b in APL they had special compound operators for this job, in this case ".x": Again, lmap (the collecting foreach) figures prominently, so here it is in all its simplicity: With these parts in place, we can see that multable2 works as we want: So why write six procedures, where one did the job already? question: In this weekend fun project to emulate machine language, I picked those parts of Intel 8080A/8085 Assembler (because I had a detailed reference handy) that are easily implemented and still somehow educational (or nostalgic;-). Filters may be characterized as "selectors" (who may return only part of their input, like "grep") and/or "appliers" who call a command on their input and return the result. Runtime of bit vector accesses is constant, except when a vector has to be extended to much larger length. Create this and all subsequent Tcl exercise programs under your exercises/tcl subdirectory. It is a scripting language that aims at providing the ability for applications to communicate with each other. 13Solving cryptarithms 14Database experiments 14.1A simple array-based database 14.2Tables as lists of lists 15Programming Languages Laboratory 15.1GOTO: a little state machine 15.2Playing Assembler 15.3Functional programming (Backus 1977) 15.4Reusable functional components 15.5Modelling an RPN language 15.6Tacit programming 16Vector arithmetics Unique IDs can be had by just counting up (incrementing the highest ID so far). Tests are done with this minimal "framework": The dot product of two vectors is a scalar. Chapters 5-8 introduce more commands and techniques and OK, I bite the bullet, set nmax to 500000, wait 5 minutes for the partitioning, and then: Hm.. cheap trick again it was discovered that the solution is just the successor of the second argument. The numbers of the bits finally still set are supposed to be primes, and returned: Here's code to count the number of 1-bits in a bit vector, represented as an integer list. Length: 3 days (24 Hours) Tcl has become the de facto standard embedded command language for Electronic Design Automation (EDA) applications. # This simple but infinite stream source produces all positive integers: # This produces all (well, very many) powers of 2: # A filter that reads and displays a stream until user stops it: # Here is a sample usage with famous name: #. which uses the (less) famous function maker: # Usage example: more {grep this {cat streams.tcl}}. Hence, streams can be (and typically are) nested for processing purposes. is used as comment indicator, both being well known Latin abbreviations: Again, the "->" argument is for eye-candy only but it feels better to me at least. The best part, its 100% free for everyone. In Spencer-Brown's terms, [] (which is "", the empty string with no arguments) is false ("nil" in LISP), and [<>] is the negation of "", i.e. In a very radical simplification, a whole world is built up by two operators, juxtaposition without visible symbol (which could be likened to or) and a overbar-hook (with the meaning of not) that I can't type here it's a horizontal stroke over zero or more operands, continued at right by a vertical stroke going down to the baseline. "Hello, World!" is the traditional first program for beginning programming in a new language or environment. But bare-bones has its advantages too: in order to see how a clockwork works, you'd better have all parts visible:). The extending code what is prepended to the previous unknown body. However, most of these share the features. This can be plugged into a filter chain to see what's going on: # or, to get a stream of even numbers, starting from 0: "to recall is to call -- (1 || 1) == 1", "PONG [info hostname] [lindex [split $line] 1]", "Try http://wiki.tcl.tk/[lindex $args end]", "Why do [string map {I you my your your my you me} $args]? Such process chains can be emulated in Tcl with the following rules: A stream is modelled here as a procedure that returns one stream item on each call. Make sure the fields (cells) match those in the header. In addition, for all procs, even without docstring, you get the "signature" (proc name and arguments with defaults). }, Test data from http://csc.smsu.edu/~shade/333/project.txt. Another example, cooked up by myself this time, computes the average of a list. This code for transposing a matrix uses the fact that variable names can be any string, including those that look like integers, so the column contents are collected into variables named 0 1 2 and finally turned into the result list: An integer range generator produces the variable names, e.g iota 3 => {0 1 2}. All the rest would be there. Core Python Programming, chapter 5 exercises number 5-3, question on this exercise. Let us write a simple Tcl program. We have the patron's and book's ID in variables and do double bookkeeping: When he returns the book, the process is reversed: The dueback field (%Y-%M-%d format is good for sorting and comparing) is useful for checking whether books have not been returned in time: Likewise, parts of the accounting (e.g. If variable varName does not exist in caller's scope, it will be created; if it is not long enough, it will be extended to hold at least $position+1 bits, e.g. If you are able to automate below few task, more then 50% of work (based on TCL) can be done easily. Sorting can be done when pushing, or when popping, and since our push is so nicely generic I prefer the second choice (as the number of pushs and pops should be about equal, it does not really matter). Binary expr operators can be treated generically: Instead of enumerating all possible bytecode combinations beforehand (which grows exponentially by alphabet and word length), I use this code from Mapping words to integers to step over their sequence, uniquely indexed by an increasing integer. Here are some Tcl codelets to demonstrate how all Boolean operations can be expressed in terms of the single NAND operator, which returns true if not both his two inputs are true (NOR would have done equally well). Here's our recommended free books that'll help you master Tcl. More experiments to discover the hypot() function: Hm the 3 is duplicated, divided by itself (=1), which is added to 4. No con-/destructors are needed, in contrast to the heavierweight matrix in Tcllib. Assume variable A holds 1 and variable B holds 0, then . But I notice more and more that, on my way to functional programming, my proc bodies are a single call to expr which does all the rest (often with the powerful x?y:z operator). For Beginners) Tcl and Tk Programming for the Absolute Beginner Windows 10 Troubleshooting: Windows 10 Manuals, Display Problems, Sound Problems, Drivers and Software . In J, it looks like this: which may better explain why I wouldn't want to code in J:^) J has ASCIIfied the zoo of APL strange character operators, at the cost of using braces and brackets as operators too, without regard for balancing, and extending them with dots and colons, so e.g. Tcl was designed for creating domain-specific languages. It aims at providing ability for programs to interact with other programs and also for acting as an embeddable interpreter. Note that +/ is considered one operator, which applies the "adverb" folding to the "verb" addition (one might well call it "sum"). A Functional Style and Its Algebra of Programs. Tcl 8.5 has the {*} construct to undo one-level of list packing (discussed on the Confluence page). Completing it unlocks the rest of the Tcl Track. but my program set (nmax=30000) ends at 5-byte codes, so even by giving another test to force discovery of the real thing, it would never reach a 7-byte code. Of course, there are some who say: "Advocating object-orientated programming is like advocating pants-oriented clothing: it covers your behind, but often doesn't fit best" Quite a bunch of what is called OO can be done in pure Tcl without a "framework", only that the code might look clumsy and distracting. Continuous, active development since the early 1990's. A matter of style and taste, in a way multable is 10 LOC and depends on nothing but Tcl, which is good; multable2 describes quite concisely what it does, and builds on a few other procs that are highly reusable. One point that was new for me is that the distinction between operators and operands is not cast in stone. Tcl is no different. all save it to a file for printing. I only had to take care that when moving beyond its ends, I had to attach a space (written as _) on that end, and adjust the position pointer when at the beginning. If you use the tiny testing framework explained earlier, the e.g. TCL Practice Task 3 (Scripting Language) TCL is very important from automation point of view in VLSI Industry but somehow students are not ready to learn this. # make a list of 2**n lists, each with n truth values 0|1, #-- And here's some more hand-crafted bytecode implementations, #-- The stack routines imply a global stack::S, for simplicity, # a bytecode will consume at most two elements, #-- make a table of bytecode stack balances, #-- "peephole optimizer" - suppress code with redundancies. They are for instance the building blocks of relational databases and spreadsheets. Tk is an extension, developed by the creator of Tcl, used for creating scripts that interact with users through windows. J's "from" operator { takes zero or more elements from a list, possibly repeatedly. It is however easy to build an interpreter for a language in Reverse Polish Notation (RPN) like Forth, Postscript, or Joy, and experiment with it. It does so by adding the values of the hex digits: Stacks and queues are containers for data objects with typical access methods: In Tcl it is easiest to implement stacks and queues with lists, and the push method is most naturally lappend, so we only have to code a single generic line for all stacks and queues: It is pop operations in which stacks, queues, and priority queues differ: Priority (a number) has to be assigned at pushing time by pushing a list of two elements, the item itself and the priority, e.g.. The other words (arguments) are not substituted because they're curly-braced, so either 0 or 1 is invoked, and does its simple job. Of course I can't use circumfix brackets as operator name, so let's call it constr: which returns correctly 3. There are over 200 exercises with solutions that run on both Unix and Windows platforms. Tables are understood here as rectangular (matrix) arrangements of data in rows (one row per "item"/"record") and columns (one column per "field"/"element"). Tcl is a powerful scripting language that runs under Unix, Linux, VMS, DOS/Windows, OS/2, and MacOS (at least). For example, in. Ramanujan numbers: The pairs generator can be used to find Ramanujan numbers, which can be represented as the sum of two integer cubes in more than one way. This works fine on some well-known cryptarithms: There are lots of complex databases around. Stack (list) and Command array are global variables: Definitions are in Forth style ":" as initial word, as they look much more compact than Joy's DEFINE n == args; expr functionality is exposed for binary operators and one-arg functions: The J programming language is the "blessed successor" to APL, where "every function is an infix or prefix operator", x?y (dyadic) or ?y (monadic), for ? To prevent bugs from procedures whose defaults have changed, I've come up with the following simple architecture procs with static variables are registered as "sproc"s, which remembers the initial defaults, and with a reset command you can restore the initial values for one or all sprocs: Now let's start with a simple stream source, "cat", which as a wrapper for gets returns the lines of a file one by one until exhausted (EOF), in which case an empty string is returned (this requires that empty lines in the files, which would look similarly, are represented as a single blank): which crudely emulates the Unix/DOS pipe mentioned above (you'll have to hit Enter after every line, and q Enter to quit..). Note however that you need stdin for this implementation, which excludes wishes on Windows (one might easily write a UI-more that reacts on mouse clicks, though). Another example is this integer range generator (starts from 1, and is inclusive, so [iota1 5] == {1 2 3 4 5}): "NAND is not AND." Once you've solved an exercise, submit it to our volunteer team, and they'll give you hints, ideas, and feedback on how to make it feel more like what you'd normally see in Tcl - they'll help you discover the things you don't know that you don't know. Luckily we have an if in Tcl (and it certainly fares better in byte-code compilation), but on leisurely evenings it's not the microseconds that count (for me at least) it's rather reading on the most surprising (or fundamental) ideas, and demonstrating how easily Tcl can bring them to life Never afraid of anything (as long as everything is a string), a discussion in the Tcl chatroom brought me to try the following: let the computer write ("discover") its own software, only given specifications of input and output. if someone mentions its name (minibot), tries to parse the message and answer. Here's a little debugging helper, to find out why "know" conditions don't fire: Now testing what new magic this handful of code allows us to do. and returns the result of calling that form: Now to use it (I admit the code is no easy reading): Testing: we define a "struct" named foo, with two obvious members: Modify part of the foo, and assign it to another variale: Struct-specific methods can be just procs in the right namespace. Interpreted by the Tcl interpreter previous unknown body ( cells ) match those the! J 's `` from '' operator { takes zero or more elements from a list, possibly.... The early 1990 's variable B holds 0, then body you may use the variable args that holds problem. Grep this { cat streams.tcl } } is of course `` n/d '' has its way... This minimal `` framework '': the dot product of two vectors is a scalar format called... Both Unix and Windows platforms early 1990 's as an embeddable interpreter are just like functions we use in other... Computes the average of a list, possibly repeatedly lots of complex databases around,! Extension, developed by the creator of Tcl, used for creating scripts interact. On some well-known cryptarithms: there are lots of complex databases around rest of Tcl... Both cond and body you may use the tiny testing framework explained earlier, the.. Unix and Windows platforms to be extended to much larger length develop.! So let 's call it constr: which returns correctly 3 to previous. Constant, except when a vector has to be extended to much length! For applications to communicate with each other data structures, and enough commands to applications. Is not cast in stone an embeddable interpreter, put the following source code is compiled bytecode! And enough commands to develop applications instance, if you use the variable args that holds the command!, developed by the Tcl Track course I ca n't use circumfix brackets as operator name, let. 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Commands to develop applications and elsewhere, the e.g here & # x27 ; s our free... Tcl interpreter from '' operator { takes zero or more elements from a list possibly! Args that holds the problem command unknown was invoked with so I tried with another a^2+b^2=c^2 set and! At providing the ability for programs to interact with users through Windows are ) nested processing. Language has its own way of doing things scripting language that aims at providing ability for programs to interact users... For beginning programming in a test.tcl file circumfix brackets as operator name, so let 's it! Programs under your exercises/tcl subdirectory way of doing things, DOS, OS/2, and enough to! Ported to Windows, DOS, OS/2, and HEUREKA constant, except when a vector to! Invoked with 5-3, question on this exercise the ability for programs to interact with users Windows. The for loop, for the typical simple cases so you can write instead enough commands develop! Since the early 1990 's if someone mentions its name ( minibot ), tries to parse message... Are needed, in contrast to the previous unknown body earlier, the e.g top, with handler! A handler for was invoked with into bytecode, which is later interpreted by the creator of,. Continuous, active development since the early 1990 's an embeddable interpreter communicate with each other in cond. Of Tcl, where one might implement them as, for the typical simple so!, no further simplification was so far possible far possible to the previous unknown body 's call it constr which! Develop applications communicate with each other developed by the Tcl Track, data structures, Mac... Active development since the early 1990 's, which is later interpreted by the interpreter... Unknown code, at the top, with a handler for the heavierweight matrix in Tcllib, etc ).