site/contents/learn.md
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----- content-type: "page" title: "Learn" ----- {@ _defs_.md || 0 @} {{learn-links}} {{m}} is a stack-based, concatenative programming language that uses postfix notation. If you already know [Forth](http://www.forth.org/), [Factor](http://factorcode.org/) or [Joy](http://www.kevinalbrecht.com/code/joy-mirror/), or if you ever used an [RPN](https://en.wikipedia.org/wiki/Reverse_Polish_notation) calculator, then min will look somewhat familiar to you. If not, well, here's how a short min program looks like: ; This is a comment (1 2 3 4 5) (dup *) map This program returns a list containing the square values of the first five integer numbers: (1 4 9 16 25) Let's see how it works: 1. First, a list containing the first five integers is pushed on the stack. 2. Then, another list containing two symbols (`dup` and `*`) is pushed on the stack. This constitutes a quoted program which, when executed duplicates the first element on the stack — this is done by `dup`— and then multiplies — with `*`— the two elements together. 3. Finally, the symbol `map` is pushed on the stack. Map takes a list of elements and a quoted program and applies the program to each element. Note that: * There are no variable assignments. * elements are pushed on the stack one by one. * Parentheses are used to group one or more elements together so that they are treated as a single element and they are not evaluated immediately. * *Symbols* (typically single words, or several words joined by dashes) are used to execute code that performs operations on the whole stack. Unlike more traditional programming languages, in a concatenative programming language, there is no inherent need for variables or named parameters, as symbols act as stack operators that consume elements that are placed in order on top of a stack. {#link-learn||data-types||Data Types#} |