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Paradigm(s) imperative
Designed by cyanidesDuality
Appeared in 2020
Computational class Turing complete
Reference implementation On Github
Major implementations None
File extension(s) .tail

Tailor is a string-based esoteric programming language created by cyanidesDuality in 2020.


Tailor is a string-based esoteric programming language. As such, it is not recommended to program anything involving numeric calculations in Tailor. It could be used to program text adventure games, but really, it isn’t recommended to program much in Tailor. File extensions for Tailor patterns are .tl or .tail. Tailor is forgiving; any errors or unknown commands are handled by skipping over the error like the command that caused the error never existed. Tailor officially recognises the # character as its comment; however, because of the forgiving behavior detailed above, as long as a line doesn’t start with a Tailor command it can be treated like a comment.

Syntax and Terms

Tailor introduces some unique syntax for its programs; this is to make the language more esoteric.
Tailor fabrics are the equivalent of variables; they can store one string.
Tailor conditions are the equivalent of Boolean variables; they can store one value which can be true or false.
Tailor patterns are the equivalent of programs.
Tailor procedures are the equivalent of functions.
A Tailor is the person creating a Tailor pattern; this is not to be confused with Tailor itself.

Frames and Procedures

A frame contains all the information in a Tailor pattern. Whenever anything is created in a Tailor pattern, like a fabric or a condition, it is stored in the current frame. When a procedure is called, it creates a new frame whose parent is the previous frame; the arguments the procedure is passed are stored in the new frame as well.

For example, if there is a fabric, foo, and procedure f with argument x is called with foo, then the value of foo is copied out of the current frame and copied into the new frame under the name of x. Values referenced in commands are always checked at the highest level first; in the previous example, if a fabric, x, was present in the outermost frame, the procedure would switch from rewriting the fabric foo that was renamed to x to rewriting the fabric x.

Note that the names of fabrics are never actually changed in a Tailor pattern. During a procedure, fabrics are not actually changed; only their “alias fabrics” are, and the values are copied back after execution.


In this table, required arguments are shown in bold italic and optional arguments are shown in regular bold.

Name and Usage Function
gather Takes input from the user and stores it in fabric materials.
sell Takes fabric garment, prints it, and clears it.
stop Halts program execution.
end Halts execution of current procedure; behaves like stop command if not in a procedure. Does not exit out of while loops.
notch name Creates a notch with name name that can be used in see commands.
see position If position is an integer, this command goes to line number position. Otherwise, this command goes to the notch with name position.
hem name Interprets fabric with name name as Unicode; for example, foo\u2756bar would become foo❖bar.
condition name = fabric flags regex update Checks if fabric matches regex with flags and creates a new condition, name, with the value of that expression. If update is set, this is updated after each pattern step; otherwise, it is evaluated once and its value is then not changed if the referenced fabric changes. For example, condition foo = checking - /A/ update checks whether fabric checking has any occurrences of the string A in it, and sets condition foo accordingly, updating each pattern step.
condition name = not condition update Should be self-explanatory.
condition name = fabric 1 == fabric 2 update Checks if fabric 1 and fabric 2 are equal.
condition name = condition 1 operation condition 2 update Should be self-explanatory. Supported operations are and, or, and xor.
if ( condition ){ Checks if condition is true and executes code block accordingly.
while ( condition ){ Loops while condition is true.
bleach fabric Strips fabric of any ANSI color codes.
dye fabric color If color is an integer, this command colors fabric with the corresponding ANSI color code. Otherwise, the color code used is the value of the fabric color. In this case, if color is not a valid fabric or the value of color is not an integer, the color code used is 255 instead.
embroider fabric flags string Writes string to fabric. Supported flags are a and p, which respectively append and prepend the string to fabric instead of overwriting it. In case of -ap, both are applied and fabric is "wrapped" with string.
copy fabric 1 flags regex fabric 2 Copies the parts of fabric 1 that match regex with flags to fabric 2. The a and p flags mentioned before can also additionally be set. Note that flags and regex come as a set; either both flags and regex are included or neither are.
type name = contents Creates a new type with name name and contents contents. For example, type vowels = ["a","e","i","o","u"] creates a new type named vowels with the contents "a","e","i","o","u". ALWAYS use double quotes.
type name = type 1 + type 2 Creates a new type with name name and with contents equal to type 1 prepended to type 2. Using the previous example, type vowelY = vowels + ["y"] creates a new type with the contents "a","e","i","o","u","y", and type foo = vowels + vowelY creates a new type with the contents "a","e","i","o","u","y","a","e","i","o","u"
replace fabric flags type 1 type 2 Goes through fabric and replaces all occurrences of an element from type 1 with the corresponding element from type 2. Supported flags are a,p, and g. g is the global flag; without it, only the first occurrence is replaced.
alter fabric flags regex replace Finds all occurrences of regex with flags in fabric and replaces them with string replace. If both flags and regex are empty, this command acts like embroider fabric replace. Supported flags are a,p, and g.
procedure name ( arguments ){ Creates a new procedure, name, with arguments whose code is the code block after this command.
do name ( arguments ) Does procedure name with arguments.
variation path Imports a file with relative path path , running it and copying its functions. For example, variation examples/reversing.tail would create the functions reversing.shunt and reversing.reverse, also executing any additional code.


Hello, world!

embroider garment "Hello, world!"

Cat program

condition isEmpty = materials - /./
condition isNotEmpty = not isEmpty
while ( isNotEmpty ){
    copy materials garment
    condition isEmpty = materials - /./
    condition isNotEmpty = not isEmpty


copy materials garment
condition didInputOne = materials - /1/
while ( didInputOne ){
    embroider garment "1"

All Caps Procedure

procedure caps (capitalising){
    type lower = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
    type upper = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"]
    replace capitalising -g lower upper

Alternatively, swap lower and upper on line four to create an all-lowercase procedure.

How to use in a pattern:

copy materials alter
do caps (alter)
copy alter garment


Clone this repository or download tailor.py directly.

Either run using Python (version 3):

python3 tailor.py <pattern.tail>

Or, ensure that the file is executable and in your PATH:

tailor.py <pattern.tail>


Many thanks go out to LyricLy for showing me how to do regular expressions in Python and general help, and to tripodsan for general code debugging.