R-expressions or Rich Expressions is a language inspired by S- and M-expressions. The toolkit is written with JavaScript and contains:
- ✅ Tokenizer,
- ✅ Parser,
- ✅ Traverser,
- ✅ Transformer.
Tokenizer and parser support streaming mode with byte-per-byte input and could be used for REPL creation.
R-expressions could be used for:
- Lisp-like programming languages creation.
- Language prototyping.
- Transpilation.
(pseudo-lang ^1.0)
import({Console} from Core.Io)
Console.log('Hello, %s!' 'World')
R-Expressions contains symbols, strings, lists, calls and comments.
Symbol is a sequence of characters without whitespaces, single quotes or parenthesis. While whitespace, semicolon, quote or open parenthesis could be escaped by backslash.
These are all symbols:
true
1_000_000
^1.*
Console.log
http://github.com/rumkin/r-expressions
~/memories/summer\ vacation\ 2019/
<node>
String is a sequence of characters surrounded by single quote '.
Single quote within a string should be escaped with a backslash \.
And backslash could be escaped by another backslash \\. String could contain new lines.
'This is a string'
'Hello! I\'m a string too.'
'This is a multiline
string'
List is a type which can contain other types: symbols, strings, lists, and calls:
R-expressions has three types of lists round, square, and figure, this lists are enclosed with round, square, or figure parenthesis respectively. They can be used to separate semantic.
; Round parenthesis list
(null true 1_234 'Hello')
; Figure parenthesis list
{x: 1 y: 2 z: 3}
; Square parenthesis list
[1 2 3 4 5]
; Mixed
[a (1 {2} 3) b]
; Empty
()
⚠️ There should be a space between the closing parenthesis of a list and the opening of a following one. While this code{} {}is correct, the next one{}{}is not. Look at Call type.
Call is a type which specifies function call and is presented by symbol followed by a list:
print('Hello world')
Calls could be chained, if there is no space between lists in a sequence:
curry(print 'Hello, %s')('World')
; or
print('Hello, %s' ?)('World')
Lists types could be mixed for different semantics creation:
; HTML like code
div{class: !['badge' 'badge-round' 'badge-red']}(
p('Users count: 1')
)
Comment is a line of text prepended with a semicolon ;. Comment ends with new line char \n.
; Hi! I'm a comment. I can help you to describe your program
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