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The Déjà Vu programming language
C Python C++
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docs
vm
.gitignore
GRAMMAR.bnf
LICENSE
README.md
annotate.py
bytecode.py
collect.py
context.py
convert.py
depgraph.py
dis.py
dvasm.py
dvc.py
errors.py
flatten.py
func.py
gencompilerc.py
genstdc.py
ifelse.py
loop.py
nodes.py
parse.py
strquot.py
trycatch.py
v2a.py

README.md

Déjà Vu

It is a programming language. Stack-based. Semi-functional. Backwards. Inspired by Python and Forth. I'm talking about Déjà Vu.

Setting up the virtual machine

$ cd vm/
$ make
$ cd ..

Running things

Assuming you have a module called yourfile.deja, you can compile and run it with:

$ vm/vu yourfile.deja

Examples

Hello world

!print "Hello world!"

Fibonacci

fib a:
    if > 1 a:
        fib - 1 a
        fib - 2 a
        +
    elseif = a 1:
        1
    else:
        0

Quine

"!print !. dup"
!print !. dup

Fractions

. * 1/3 3/2 # prints 1/2

Grammar

If you know what BNF is, here's the one for Déjà Vu:

Program ::= <Block>*

Block ::= <Head> ":" <NewLine>+ (<Indentation> <Block>)+
        | <Line> <NewLine>+
        | <IfBlock>
        | <TryBlock>

IfBlock ::= "if" <Space> <Line> ":" <NewLine>+ (<Indentation> <Block>)+
            ("elseif" <Space> <Line> <Space>? ":" <NewLine>+ (<Indentation> <Block>)+)*
            ("else" <Space>? ":" <NewLine>+ (<Indentation> <Block>)+)?

TryBlock ::= "try" <Space>? ":" <NewLine>+ (<Indentation> <Block>)+
             ("catch" (<Space> <ProperWord>)+ <Space>? ":" <NewLine>+ (<Indentation> <Block>)+)*

Head ::= "while" <Space> <Line>
       | "for" <Space> <ProperWord> (<Space> <Line>)? <Space>?
       | "repeat" <Space> <Line>
       | "func" <Space> <ProperWord> <Arguments>
       | "local" <Space> <ProperWord> <Arguments>
       | "labda" <Arguments>
       | <ProperWord> <Arguments>

Indentation ::= (" " | <Tab>)*

Line ::= (<Word> (<Space> <Word>)*)? <Space>?

Arguments ::= (<Space> <ProperWord>)* <Space>?

Space ::= (" " | <Tab>)+

Word ::= ProperWord
       | Get
       | Identity
       | String
       | Number
       | Fraction

Get ::= "@" <ProperWord>?

Identity ::= ":" <ProperWord>?

ProperWord ::= <Char>+

String ::= '"' <StringChar>* '"'

Number ::= '-'? <Digits> ('.' <Digits>)?

Fraction ::= '-'? <Digits> '/' <Digits>

Digits ::= ('0'..'9')+

Char ::= any non-whitespace, non-# character

StringChar ::= any character other than a double quote
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