mtac
Reverse the order of an array
mtac
takes input from stdin and reverses the order of it.
It’s name is derived from a program called tac
- a tool that functions like cat
but returns the contents in the reverse order. The difference with the mtac
builtin is that it is data-type aware. So it doesn’t just function as a replacement for tac
but it also works on JSON arrays, s-expressions, and any other data-type supporting arrays compiled into Murex.
<stdin> -> mtac -> <stdout>
» ja [Monday..Friday] -> mtac
[
"Friday",
"Thursday",
"Wednesday",
"Tuesday",
"Monday"
]
# Normal output (without mtac)
» ja [Monday..Friday]
[
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday"
]
Please bare in mind that while Murex is optimised with concurrency and streaming in mind, it’s impossible to reverse an incomplete array. Thus all all of stdin must have been read and that file closed before mtac
can output.
In practical terms you shouldn’t notice any difference except for when stdin is a long running process or non-standard stream (eg network pipe).
mtac
list.reverse
2darray
: Create a 2D JSON array from multiple input sourcesa
(mkarray): A sophisticated yet simple way to build an array or listappend
: Add data to the end of an arraycount
: Count items in a map, list or arrayja
(mkarray): A sophisticated yet simply way to build a JSON arrayjsplit
: Splits stdin into a JSON array based on a regex parametermap
: Creates a map from two data sourcesmsort
: Sorts an array - data type agnosticprefix
: Prefix a string to every item in a listprepend
: Add data to the start of an arraypretty
: Prettifies JSON to make it human readablesuffix
: Prefix a string to every item in a listta
(mkarray): A sophisticated yet simple way to build an array of a user defined data-typeThis document was generated from builtins/core/lists/mtac_doc.yaml.
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