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Language

This page describes the syntax and core types of the language.

Comments

Comments start with a ; and end at the end of a line

; This is a comment
(+ 1 2) ; This is also a comment

Data types

The core types are backed by their corresponding Ruby classes. This can be seen by doing (.class 5).

integer

A whole number.

1
-42
0

decimal

A decimal number.

3.56
-0.5

boolean

The value true or false.

true
false

nil

The "null" or "no value" type.

nil

text

Text of any length. There is a shorthand syntax that can be used when the string does not contain any whitespace - this makes the syntax in dicts nicer, for example.

It supports these escape characters:

  • \n - a newline
  • \t - a tab
  • \\ - a literal \
  • \" - a literal "
"some text" ; => "some text"

; Shorthand version
:text ; => "text"

; Using escape characters
;
; Note that they will still look escaped when returned in the REPL,
; however, if you print them you will get the literal text.
"text with \" and \\ in it" ; => "text with \" and \\ in it"

(println "text with \" and \\ in it")
; text with " and \ in it

list

A heterogeneous (allows mixed types) list of values, can be created with the list function. This type is also used to call a function. There is no difference between a list of data and a "list of code", a.k.a. form.

(list 1 2 :three) ; => (1 2 "three")

; The first item in the list will be called with the rest of the list as arguments:
(println "Hello, " "world!")

dict

A dictionary (a.k.a. hash-map) of keys that map to values, can be created with the dict function.

; Here we use the shorthand text syntax as keys
(dict :one 1 :two 2) ; => {"one" 1, "two" 2}

symbol

Used to name other things (see def), but can be obtained in itself by quoting (see quote).

Symbols should be lowercase, with words separated by dashes.

; A symbol will resolve to what it has been defined as
symbol

; To obtain a symbol by itself, you have to quote it
'symbol

'a-long-symbol-name

Ruby interoperability

You can access Ruby classes and modules, to access nested ones use /. To call Ruby methods, simply prepend a dot to the method name, and pass the object as the first parameter.

(.ceil Math/PI) ; => 4

(.to_i "010101" 2) ; => 21