Category:TXR: Difference between revisions

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TXR is a new language implemented in C, running on POSIX platforms such as Linux, Mac OS X and Solaris as well as on Microsoft Windows. It is a dynamic, high level language originally intended for "data munging" tasks in Unix-like environments, particularly tasks requiring accurate, robust text scraping from loosely structured documents.

The Rosetta Code TXR solutions can be viewed in color, and all on one page with a convenient navigation pane here.

TXR started as a language for "reversing here-documents": evaluating a template of text containing variables, plus useful pattern matching directives, against some body of text and binding pieces of the text which matches variables. The variable bindings were output in POSIX shell variable assignment syntax, allowing for shell code like

eval $(txr <txr-program> <args> ...)

TXR was internally based, from the beginning, on a data model based on Lisp and eventually exposed a Lisp dialect that came to be known as TXR Lisp. TXR Lisp at first complemented the pattern extraction language, extending its power, but eventually became distinct. Programs can be written in TXR Lisp with no traces of the TXR pattern language, or vice versa.

TXR Lisp is an original dialect that contains many innovative features, which orchestrate together to express neat, compact solutions to everyday data processing problems. Programmers familiar with Common Lisp will be comfortable with TXR Lisp, and there is much to like for those who use Scheme, Racket or Clojure. TXR Lisp incorporates ideas from contemporary scripting languages also; a key motivation in many of its developments is the promotion of succinctness, which is something that often isn't associated with languages in the Lisp family.

Subcategories

This category has the following 3 subcategories, out of 3 total.

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Pages in category "TXR"

The following 160 pages are in this category, out of 160 total.

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100 doors

9

99 bottles of beer

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D

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I

J

K

Keyboard input/Obtain a Y or N response

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Quine

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-{{stub}}{{language
+{{language
 |site=http://www.nongnu.org/txr/}}
+{{language programming paradigm|functional}}
+{{language programming paradigm|procedural}}
+{{language programming paradigm|object-oriented}}
+{{language programming paradigm|imperative}}
+{{language programming paradigm|declarative}}
-TXR is a new text extraction language implemented in [[C]], running on [[Linux]] (and possibly other [[POSIX]] platforms).
+TXR is a new language implemented in [[C]], running on POSIX platforms such as [[Linux]], [[Mac OS X]] and [[Solaris]] as well as on [[Microsoft Windows]]. It is a dynamic, high level language originally intended for "data munging" tasks in Unix-like environments, particularly tasks requiring accurate, robust text scraping from loosely structured documents.
+The Rosetta Code TXR solutions can be viewed in color, and all on one page with a convenient navigation pane [http://www.nongnu.org/txr/rosetta-solutions.html here].
-==Simple Query==
+TXR started as a language for "reversing here-documents": evaluating a template of text containing variables, plus useful pattern matching directives, against some body of text and binding pieces of the text which matches variables. The variable bindings were output in POSIX shell variable assignment syntax, allowing for shell code like
-Here is a very basic hello-world-type TXR query that re-implements the "free" utility:
+<code>eval $(txr <txr-program> <args> ...)</code>
-<lang txr>#!/usr/bin/txr -f
-@(next "/proc/meminfo")
-@(skip)
-MemTotal:@/ +/@TOTAL kB
-MemFree:@/ +/@FREE kB
-Buffers:@/ +/@BUFS kB
-Cached:@/ +/@CACHED kB
-@(skip)
-SwapTotal:@/ +/@SWTOT kB
-SwapFree:@/ +/@SWFRE kB
-@(next `!echo $(( @TOTAL - @FREE ))`)
-@USED
-@(next `!echo $(( @USED - @BUFS - @CACHED ))`)
-@RUSED
-@(next `!echo $(( @FREE + @BUFS + @CACHED ))`)
-@RFREE
-@(next `!echo $(( @SWTOT - @SWFRE ))`)
-@SWUSE
-@(output)
-               TOTAL         USED         FREE      BUFFERS       CACHED
-Mem:    @{TOTAL -12} @{USED  -12} @{FREE  -12} @{BUFS  -12} @{CACHED -12}
-+/- buffers/cache:   @{RUSED -12} @{RFREE -12}
-Swap:   @{SWTOT -12} @{SWUSE -12} @{SWFRE -12}
-@(end)</lang>
+TXR was internally based, from the beginning, on a data model based on Lisp and eventually exposed a Lisp dialect that came to be known as TXR Lisp. TXR Lisp at first complemented the pattern extraction language, extending its power, but eventually became distinct. Programs can be written in TXR Lisp with no traces of the TXR pattern language, or vice versa.
-Sample run:
+TXR Lisp is an original dialect that contains many innovative features, which orchestrate together to express neat, compact solutions to everyday data processing problems. Programmers familiar with Common Lisp will be comfortable with TXR Lisp, and there is much to like for those who use Scheme, Racket or Clojure.  TXR Lisp incorporates ideas from contemporary scripting languages also; a key motivation in many of its developments is the promotion of succinctness, which is something that often isn't associated with languages in the Lisp family.
-<pre>$ ./meminfo.txr
-               TOTAL         USED         FREE      BUFFERS       CACHED
-Mem:          769280       647752       121528       160108       286844
-+/- buffers/cache:         200800       568480
-Swap:        1048568        18200      1030368
-</pre>
-Arithmetic is not implemented in TXR as of version 035. The above example simply continues the pattern matching across invocations of echo to borrow the shell to do math. The command
-<pre>@(next `!echo $(( @TOTAL - @FREE ))`)
-@USED
-</pre>
-means, "Next, please switch to scanning the output of this echo command with some variables substituted in. Then capture entire first line of this command into the USED variable."
-== Complex Query ==
-Here is a TXR query for computing the complete dependencies of a C source file (including system and compiler headers) on a typical GNU/Linux system, demonstrating features like parallel clauses, recursion and exception handling.
-<lang txr>@(define process_file (dir file already_visited visited_out))
-@  (local this_file next_file header_dir next_dir next_dir2 visited_out_next)
-@  (bind this_file `@dir@file`)
-@  (none)
-@    (bind already_visited this_file)
-@  (end)
-@  (merge already_visited already_visited this_file)
-@  (next this_file)
-@  (collect)
-@    (cases)
-#include "@*header_dir/@next_file"
-@      (bind next_dir `@dir@header_dir/`)
-@    (or)
-#include "@next_file"
-@      (bind next_dir dir)
-@    (or)
-#@/ */include <@next_file>
-@      (bind next_dir sys_includes)
-@      (bind next_dir2 gcc_includes)
-@    (or)
-#@/ */include <@*header_dir/@next_file>
-@      (bind next_dir `@sys_includes@header_dir/`)
-@      (bind next_dir2 `@gcc_includes@header_dir/`)
-@    (or)
-#@/ */include_next <@next_file>
-@      (bind next_dir gcc_includes)
-@    (or)
-#@/ */include_next <@*header_dir/@next_file>
-@      (bind next_dir `@gcc_includes@header_dir/`)
-@    (end)
-@    (try)
-@      (process_file next_dir next_file already_visited visited_out_next)
-@      (merge already_visited already_visited visited_out_next)
-@    (catch)
-@      (try)
-@        (process_file next_dir2 next_file already_visited visited_out_next)
-@        (merge already_visited already_visited visited_out_next)
-@      (catch)
-@      (end)
-@    (end)
-@  (end)
-@  (bind visited_out this_file)
-@  (try)
-@    (flatten visited_out_next)
-@    (merge visited_out visited_out visited_out_next)
-@  (catch)
-@  (end)
-@(end)
-@(next :args)
-@(cases)
-@*dir/@*file.@suffix
-@  (bind directory `@dir/`)
-@(or)
-@*file.@suffix
-@  (bind directory "")
-@(end)
-@(next `!gcc -print-search-dirs`)
-install: @gcc_install
-@(bind gcc_includes `@{gcc_install}include/`)
-@(bind sys_includes "/usr/include/")
-@(process_file directory `@file.@suffix` nil list_out)
-@(output)
-@(rep) @list_out@(first)@file.o:@(end)
-@(end)</lang>
-Sample run:
-<pre>$ txr dep.txr match.c
-match.o: /usr/include/stdio.h /usr/include/features.h /usr/include/sys/cdefs.h /usr/include/bits/wordsize.h /usr/include/gnu/stubs.h /usr/include/gnu/stubs-32.h /usr/lib/gcc/i586-redhat-linux/4.4.1/include/stddef.h /usr/include/bits/types.h /usr/include/libio.h /usr/include/_G_config.h /usr/include/wchar.h /usr/lib/gcc/i586-redhat-linux/4.4.1/include/stdarg.h /usr/include/bits/wchar.h /usr/include/wctype.h /usr/include/endian.h /usr/include/bits/endian.h /usr/include/bits/byteswap.h /usr/include/xlocale.h /usr/include/bits/wchar2.h /usr/include/bits/wchar-ldbl.h /usr/include/gconv.h /usr/include/bits/stdio-lock.h /usr/include/bits/libc-lock.h /usr/include/pthread.h /usr/include/sched.h /usr/include/time.h /usr/include/bits/time.h /usr/include/bits/sched.h /usr/include/signal.h /usr/include/bits/signum.h /usr/include/bits/siginfo.h /usr/include/bits/sigaction.h /usr/include/bits/sigcontext.h /usr/include/asm/sigcontext.h /usr/include/linux/types.h /usr/include/linux/posix_types.h /usr/include/linux/stddef.h /usr/include/asm/posix_types.h /usr/include/asm/types.h /usr/include/asm-generic/int-ll64.h /usr/include/bits/sigstack.h /usr/include/sys/ucontext.h /usr/include/bits/pthreadtypes.h /usr/include/bits/sigthread.h /usr/include/bits/setjmp.h /usr/include/bits/libio-ldbl.h /usr/include/bits/stdio_lim.h /usr/include/bits/sys_errlist.h /usr/include/getopt.h /usr/include/ctype.h /usr/include/bits/stdio.h /usr/include/bits/stdio2.h /usr/include/bits/stdio-ldbl.h /usr/include/stdlib.h /usr/include/bits/waitflags.h /usr/include/bits/waitstatus.h /usr/include/alloca.h /usr/include/bits/stdlib.h /usr/include/bits/stdlib-ldbl.h /usr/include/string.h /usr/include/bits/string.h /usr/include/bits/string2.h /usr/include/bits/string3.h /usr/include/assert.h /usr/include/errno.h /usr/include/bits/errno.h /usr/include/linux/errno.h /usr/include/asm/errno.h /usr/include/asm-generic/errno.h /usr/include/asm-generic/errno-base.h /usr/include/dirent.h /usr/include/bits/dirent.h /usr/include/bits/posix1_lim.h /usr/include/bits/local_lim.h /usr/include/linux/limits.h /usr/include/setjmp.h config.h lib.h gc.h unwind.h regex.h /usr/include/limits.h /usr/lib/gcc/i586-redhat-linux/4.4.1/include/limits.h /usr/lib/gcc/i586-redhat-linux/4.4.1/include/syslimits.h /usr/include/bits/posix2_lim.h /usr/include/bits/xopen_lim.h stream.h parser.h txr.h utf8.h filter.h match.h</pre>