The
Tea shell for the JVM has been available as version 3.2.2 for some months now.
There is no problem running the shell under Windows if you had Tea 3.1.0 up and running.
The first problem is that 3.2.2 includes no TEA.BAT in the
tgz file. Just get the old 3.1.0, extract the bat file and update it to suit your install.
Tea must find a GNU jar for regexp and a Xerces jar for XML parsing. I reference them explicitly in a temp CLASSPATH in that BAT, e.g.,
set CLASSPATH=%TEA_BASE_DIR%;%TEA_BASE_DIR%\xerces-1.4.4.jar;%TEA_BASE_DIR%\gnu-regexp-1.0.8.jar;%CLASSPATH%
Tea is intended to bring multi-paradigm programming to the JVM. It is a java-based functional langauge with extensions for procedures and classes. This is another language intended to be component 'glue'. The selling point is that it is in java.
Other multi-paradigm languages either have their own compiler written in C or are using libraries implemented in C. Tea is java so one positive is that you get javadocs. The tea reference javadoc lists about 20 functions as the language core.
As a functional language Tea is intended to make the use of closures easy: functions are first-class objects as in JavaScript. In many respects the object system is like Smalltalk: members are private; methods are public. Code blocks in {} come with their contexts as closures. Every statement is at least a word which invokes a function. Lists are like Smalltalk collections: they can contain objects of mixed types. Unlike JavaScript, there is no literal notation for functions, but they can be loaded at will from jars or from raw source files using the
source word.
Variables are not pre-typed, but they must first be declared with a
define. The
define word is over-loaded 3-fold: define a variable; declare a variable to have a value; define a variable to be a function as declared. The
define word returns what it defines (it, too, is a function.) The
set! function is used to re-assign a variable and anonymous functions can be had using the
lambda function. Much like Smalltalk's
collect: there is a
map function to iteratively apply a function to a list. For lists of lists there is the function
map-apply. Unassigned vars are returned with the value
null. But note this sigil use:
define nativeParser $null
The syntax is very simple. Statements end at end-of-line. Comments start with octothorpe. You get variable values with a prefixed $ sigil. Other scripters will feel comfortable. The type tests use
function? string? symbol? int? pair? which is extended to boolean tests as
same? not-same? null? and
not-null?. Lists use parentheses and, thankfully, no commas.
Lists are very much Scheme, as in
define testPair [cons "first" "last"]
where [car $testPair] gives "first and [cdr $testPair] give "last".
List are built from such pairs; the last pair in the list references a pair where both slots are
null. With syntactic sugar our test list can be declared as
define testPair ( "first" "last" )
The Smalltalk procedural style is made possible by using the $ sigil.
For example, if you have a database connection in variable
conn then
define sqlStmt [$conn statement]
returns a statement. The difference from Smalltalk can be seen when the query is created: there is no need for a colon, as in
define dataSet [$sqlStmt query "SELECT client_id FROM new_customers"]
but what is different is the use of [...] and not as a code-block { expression }. What is happening, of course, is a command substitution as in
Tcl. The
{} are used to defer evaluation as in a while loop.
The
load function is rather like Jython: it gives access to java classes including Tea functions in those java jars.
But why would you use Tea? One possiblity is that you already know Scheme and Tcl or need a rapid way to work with closures in the JVM. But why not simply use JavaScript? One curiousity is that Tea is promoted as a language for rapid-prototyping, but in Lisbon it has been used for major banking and telco systems. But was it used only as glue code? Not at over a million lines according to Tea's own '
whitepaper'.
One observation: Tea is almost the opposite of Curl and Rebol. It is only now adding GUI and networking. But why add them if this is a scripting language for the JVM? It must be irresistable. Some people spoil their kids; some people spoil something else. And most of us seem to bloat if we are not kept on track ... and reminded that what we leave out can be as important as what we put in.
In Tea you get a hint of what the future holds if we shift away from 'C' and the OS to life with a VM.
Likely Tea will never have the momentum to break into North American markets unless it is embraced by a major player. It does have an advantage over Jython: there is no shifting Python beneath it. Then again, functional may becoming fashionable... even at Microsoft.
If you are a secret Schemer masquerading in Java or someone who can't thrive without a little Tcl, you may want to have some Tea... and lemon? Ah, right. They already added the syntactic sugar ...
PS There is another TEA which is the Tiny Encryption Algorithm and yet another Tea that is a strongly-typed templating language for managing servlets from the Disney TeaServlet project at what was once GO.COM Green tea. Black tea. Chá, anyone?
