I was inspired to write a Tcl interpreter after I realised how simple the language really was (it took me some time to become enlightened) and how elegant the API for embedding it in another program could be.
I call it a Tcl-like language because it doesn't attempt to implement all the
features of Tcl. It has several useful features though, like dict and expr
and so forth.
Due to limits in the expression evaluator you can't just write an
if- or while-statement condition like
if {$x<2} {puts "Yea"};
because the {$x<2} will be treated as a command. You should rather use
the expr command, as follows:
if {expr $x<2} {puts "Yea"};
This interpreter goes for simplicity. It uses strings to represents all
variables, with the result that it has to use atoi() and snprintf() to
convert to and from numbers when performing arithmetic. It also does a
lot of strdup()ing internally. The result is that that it could be too
slow for some tastes. Please don't hold it against me.
Another note: I have removed all checks on the return values of malloc() and
friends functions to make the interpreter a little bit leaner. I would not
recommend using the interpreter in environments where you may run out of memory.
I took some inspiration (like how the callframes are handled and several of the API functions) from Salvatore Sanfilippo's Picol Tcl interpreter, which can be found at http://antirez.com/page/picol. This is, however, a new implementation.
To make Fiz usable in different configurations, some compile time flags have been added. Define these in your environment for the desired effect.
-
FIZ_DISABLE_INCLUDE_FILES- disablesfiz_readfilefunction,includecommand and the interactive shell. Provided for embedding into other applications -
FIZ_INTEGER_EXPR- changes the floating point expression evaluation to use integers
These options are also available:
FIZ_OVERRIDE_HASH_DEFAULT_SIZE- set to override default hash size (default 512)