all repos — min @ d09f14619013d89c694d8083cb5f875b08313ef7

A small but practical concatenative programming language.

site/contents/learn-operators.md

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-----
content-type: "page"
title: "Learn: Operators"
-----
{@ _defs_.md || 0 @}

Every min program needs _operators_ to:

* Manipulate elements on the stack
* Perform operations on data
* Provide side effects (read/print to standard input/output/files, etc.)

There are two types of operators: _symbols_ and _sigils_.

_Symbols_ are the most common type of operator. A min symbol is a single word that is either provided by one of the predefined min {#link-page||reference||modules#} like `dup` or `.` or defined by the user. User-defined symbols must:

* Start with a letter or an underscore (\_).
* Contain zero or more letters, numbers and/or any of the following characters: `/ ! ? + * . _ -`

It is possible to define symbols using the {#link-operator||lang||define#} symbol. The following min program defines a new symbol called square that duplicates the first element on the stack and multiplies the two elements:

     (dup *) "square" define

Besides symbols, min provides a set of predefined _sigils_ for commonly-used symbols. For example, the previous definition could be rewritten as follows using sigils:

     (dup *) :square

A sigil like `:` can be prepended to a single-word string instead of using the corresponding symbol. Essentially, sigils are nothing more than syntactic sugar. Currently min provides the following sigils:

+
: Alias for {#link-operator||lang||module#}.
~
: Alias for {#link-operator||lang||delete#}.
'
: Alias for {#link-operator||lang||quote#}.
\:
: Alias for {#link-operator||lang||define#}. 
^
: Alias for {#link-operator||lang||call#}. 
@
: Alias for {#link-operator||lang||bind#}. 
>
: Alias for {#link-operator||lang||save-symbol#}. 
<
: Alias for {#link-operator||lang||load-symbol#}. 
&#61;
: Alias for {#link-operator||lang||quote-bind#}. 
\#
: Alias for {#link-operator||lang||quote-define#}. 
/
: Alias for {#link-operator||seq||dget#}. 
%
: Alias for {#link-operator||seq||dset#}. 
?
: Alias for {#link-operator||seq||dhas?#}.
!
: Alias for {#link-operator||sys||system#}.
&
: Alias for {#link-operator||sys||run#}.
$
: Alias for {#link-operator||sys||get-env#}. 

{#link-learn||quotations||Quotations#}