uu

The double u programming language.

Features

• Inline comments are possible with a '//'.
• Run 'dpl -pp' to see the pretty printer. This will print out the parse tree without evaluating anything. The pretty printer is a fixed-point combinator for all valid uu syntax.
• Lambdas can be passed as variables in between functions.
• Arrays with constant access time.
• Ints and Strings
• while and for loops
• recursion
• comments
• dynamic typing

Compiling and running

To compile uu, simply run

make clean
make
dpl <your input file>

Debugging

If you run into errors, and beleive it is related to the syntax, you can compile uu in debug mode.

make clean
make CFLAGS="-D uuDebug"

When you run uu programs after uu has been compiled in debug mode, the parser will print out each time it checks for an item.

Vim Syntax File

The uu.vim file will enable syntax highlighting for the uu language if you install it on your system.

" Vim Syntax File
" Language: uu
" Maintainer: Thomas Willingham
" Latest Revision: 01 Dec 2016

if exists("b:current_syntax")
    finish
endif

syn keyword basicLanguageKeywords func if else while for nil break
syn keyword builtins print println array
syn keyword stdlib stack push pop peek cons car cdr setCar setCdr min max node getParent getGrandparent setParent setLeft setRight getLeft getRight
syn match uuComment "//.*$"

hi def link basicLanguageKeywords Statement
hi def link builtins Type
hi def link stdlib PreProc
hi def link uuComment Comment

Test functions

The following make commands allow for testing of various aspects of the language.

make error1
make error1x
make error2
make error2x
make error3
make error3x
make arrays
make arraysx
make conditionals
make conditionalsx
make recursion
make recursionx
make iteration
make iterationx
make functions
make functionsx

Standard Library

These functions are ready for use in any uu program.

• cons(a, b)
• car(a)
• setCar(a)
• cdr(a)
• setCdr(a)

Stacks

• stack()
• push(item, stack)
• pop(stack)
• peek(stack)

Printing

• print(items, to, print)
• println(items, to, print)

Math

• min(a, b)
• max(a, b)

Trees

• node()
• getParent(n)
• setParent(n)
• getGrandparent(n)
• getValue(n)
• setValue(n)
• getLeft(n)
• setLeft(n)
• getRight(n)
• setRight(n)

Example function

func test () {
    wer = 5;
    if(wer == 1) {
        print("wer");
    } else if (wer == 2) {
        print("wer");
    }
    while(wer == 1) {
        wer = wer + 1;
    }
    for(i = 4309; i < 4321; i = i + 1) {
        println(i);
    }
}
test();

Parse Tree

This is the structure in which programs are parsed and then evaluated.

Grammar

// Grammar for the double u programming language

            program : expressionList

     expressionList : expression
                    | expression expressionList

         expression : expr SEMI
                    | loop
                    | if
                    | funcDef

               expr : primary
                    | primary operator expr

         optParamList : *empty*
                    | paramList

          paramList : expr
                    | expr COMMA paramList

            primary : literal
                    | OP expr CP                // nest expressions
                    | lambda
                    | ID                        // variable/func name
                    | ID OSB expr CSB           // access array
                    | ID OP optIdList CP     // call function
                    | lambda OP optIdList CP

           operator : MINUS       // -
                    | PLUS        // +
                    | DIVIDE      // /
                    | MULTIPLY    // *
                    | NOT         // !
                    | GT          // >
                    | LT          // <
                    | GTE         // >=
                    | LTE         // <=
                    | ISEQUAL     // ==
                    | AND         // &
                    | OR          // |
                    | EQUALS      // =

            literal : INT
                    | STRING

            funcDef : FUNC ID OP optIdList CP block

          optIdList : *empty*
                    | idList

             idList : ID
                    | ID COMMA idList

             lambda : LAMBDA OP optParamList CP block

               loop : while
                    | for

              block : OCB optExpresionList CCB

              while : WHILE OP expr CP block

                for : FOR OP expr SEMI expr SEMI expr CP bock

                 if : IF OP expr CP block optElse

            optElse : ELSE block
                    | ELSE if
                    | *empty*