##### Null Terminated Strings

As null terminated strings are used throughout C interfaces, their use is supported in Forth by way of several non-standard words with the convention of using Z/z to refer to such strings in names and stack comments.

    Z" ( "string" -- z ) Creates a null terminated string on the heap
    Z>S ( z -- a n ) Convert a null terminated string to a counted string
    S>Z ( a n -- z ) Conver a counted string string to null terminated (copies string to heap)

##### Raw Strings

Raw strings are provided better support using a string for the duration of the current command, without consuming heap memory.

    R" ( "string" -- a n ) Creates a temporary counted string
    R| ( string| -- a n ) Creates a temporary counted string ending with |

##### Utilities

    DUMP ( a n -- ) Dump a memory region
    SEE ( "name" -- ) Attempt to decompile a word
    VARIABLE ECHO -- Determines if commands are echoed
    REMAINING ( -- n ) Bytes remaining in Forth heap.
    DUMP-FILE ( data data# fn fn# -- ) Write contents of a file throws on error.

##### Vocabularies

{{FORTH}} uses a hybrid of Forth-79 and Forth-83 style vocabularies. By default vocabularies chain to the vocabulary in which they were defined, as in Forth-79. However, like Forth-83, `ALSO` can be used to add vocabularies to a vocabulary stack of which `CONTEXT @` is the first item. The word `ONLY` clears the vocabulary stack, but as there is no separate ONLY vocabulary, it also sets `CONTEXT` to the `FORTH` vocabulary. The word `SEALED` modifies the most recently defined vocabulary such that it does not chain. Note, this must be done before words are added to it.

    VOCABULARY ( "name" ) Create a vocabulary with the current vocabulary as parent
    FORTH ( -- ) Make the FORTH vocabulary the context vocabulary
    DEFINITIONS ( -- ) Make the context vocabulary the current vocabulary
    VLIST ( -- ) List the words in the context vocabulary (not chains)
    WORDS ( -- ) List the words in the context vocabulary (including chains)
    TRANSFER ( "name" ) Move a word from its current dictionary to the current vocabulary
                        Useful for "hiding" built-in words
    TRANSFER{ ..words.. }TRANSFER ( -- ) Transfer multiple words to the current vocabulary
    ALSO ( -- ) Duplicate the vocabulary at the top of the vocabulary stack
    PREVIOUS ( -- ) Drop the vocabulary at the top of the vocabulary stack
    ONLY ( -- ) Reset context stack to one item, the FORTH dictionary
                Non-standard, as there's no distinct ONLY vocabulary
    ORDER ( -- ) Print the vocabulary search order
    SEALED ( -- ) Alter the last vocabulary defined so it doesn't chain

##### Interpret Time Conditions

`[IF]`, `[ELSE]`, and `[THEN]` can be used to selectively compile. Used in tandem with `DEFINED?` they can be used to handle the absence of modules gracefully. Nesting is supported.

    DEFINED? ( "name" -- xt|0 ) Check if a word exists (works at compile time too).
    [IF] ( f -- ) Conditionally interpret the text the follows.
    [ELSE] ( -- ) Interpret time ELSE.
    [THEN] ( -- ) Interpret time THEN.

##### Floating-Point

Requires v7.0.6.5+

Single precision floating-point support is available as a work in progress. While initially left out in the name of minimalism, hardware support for floating-point argues some advantages to limited support.

Floating point is kept on a separate stack.

NOTE: Tasks currently don't correctly support floating point. A single floating point stack is shared by all tasks.

    FLOAT OPCODES
    -------------
    DOFLIT ( --- ) Puts a float from the next cell onto float stack.
    FP@ ( -- a )
    FP! ( a -- )
    SF@ ( a -- r ) Single precision load
    SF! ( r a -- ) Single precision store
    FDUP ( r -- r r )
    FNIP ( ra rb -- rb )
    FDROP ( r -- )
    FOVER ( ra rb -- ra rb ra )
    FSWAP ( ra rb -- rb ra )
    F0< ( r -- f )
    F0= ( r -- f )
    F+ ( r r -- r )
    F- ( r r -- r )
    F* ( r r -- r )
    F/ ( r r -- r )
    1/F ( r -- r )
    S>F ( n -- r )
    F>S ( r -- n )

    HIGH LEVEL
    ----------
    F= ( r r -- f )
    F< ( r r -- f )
    F> ( r r -- f )
    F<= ( r r -- f )
    F>= ( r r -- f )
    F<> ( r r -- f )

    SFLOAT ( -- 4 )
    SFLOATS ( n -- n*4 )
    SFLOAT+ ( a -- a+4 )
    SF, ( r -- )

    AFLITERAL ( r -- )
    FLITERAL ( r -- ) IMMEDIATE

    FCONSTANT ( r "name" )
    FVARIABLE ( "name" )

    PI ( -- r )

    FSQRT ( r r -- r )

    F.S ( -- ) Print float stack.

##### Locals

Locals allow named word local parameters and values.

    Syntax:
      { local1 local2 .. -- comment }
    or
      { local1 local2 .. }

    Locals are ordered to match the stack, examples:
    : 2OVER { a b c d } a b c d a b ;
    : MAX { a b -- biggest } a b < IF b ELSE a THEN ;

    ( Equivalent with DO and FOR )
    : POW2 { n } 1 { s } n FOR AFT s 2* to s THEN NEXT s ;
    : POW2 { n } 1 { s } n 0 DO s 2* to s LOOP s ;

Capabilities and limitations:

- Support for locals referenced inside DO and FOR loops - OK
- Support for multiple {} uses in one definition - OK
- Support for TO and +TO to modify a local
- Locals mixed with raw return stack operations (`>R R>`) - NOT OK
- Locals defined inside a DO or FOR loop - NOT OK
- The low level ANSForth word `(LOCAL)` is also supported.