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Builtin syntaxes
================
This implementation includes minimal number of builtin syntaxes. All other
constructs should be defined as user defined syntaxes in Lisp itself.
In following examples, lines starting with ``>`` represent characters
provided to input stream. Lines without starting ``>`` character represent
evaluation results written to output stream.
Available builtin syntaxes are:
* `lambda`
Definition of new user defined function.
Examples::
> ((lambda x x) 1 2 3)
(1 2 3)
> ((lambda (x) x) 1)
1
> ((lambda (x . y) y) 1 2 3)
(2 3)
* `syntax`
Definition of new user defined syntax.
Examples::
> ((syntax x x) (lambda x x) 1 2 3)
(1 2 3)
* `define`
Add new symbol binding to current context.
Examples::
> (define xyz 42)
> xyz
42
* `set!`
Change previously defined context entry.
Examples::
> (define xyz 42)
> xyz
42
> (set! xyz 24)
> xyz
24
* `begin`
Evaluate multiple expressions and return result of last expression
evaluation.
Examples::
> (begin 1 2 3)
3
* `quote`
Evaluates to provided argument.
Examples::
> (quote (1 2 3))
(1 2 3)
> '(3 2 1)
(3 2 1)
* `if`
If first argument evaluates to `thruthy` value, `if` syntax returns
result of second argument evaluation. If first argument evaluates to
`falsy` value, result of third argument evaluation is returned or
``()`` if third argument is not available.
`Falsy` values are ``0``, ``()``, ``""`` and empty symbol.
`Thruthy` values are all that are not `falsy`.
Examples::
> (if 0 1 2)
2
> (if "0" 1 2)
1
Source code
-----------
syntax.h
''''''''
.. literalinclude:: ../src_c/syntax.h
:language: c
syntax.c
''''''''
.. literalinclude:: ../src_c/syntax.c
:language: c
|
