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The following methods are recommended if you need to evaluate a Scheme expression from a Java method. (Some details (such as the ‘throws’ lists) may change.)
Initializes the Scheme environment. Maybe needed if you try to load a module compiled from a Scheme source file.
Read expressions from port, and evaluate them in the
env environment, until end-of-file is reached.
Return the value of the last expression,
or Interpreter.voidObject
if there is no expression.
Read expressions from string, and evaluate them in the
env environment, until the end of the string is reached.
Return the value of the last expression,
or Interpreter.voidObject
if there is no expression.
The sexpr is an S-expression (as may be returned by read
).
Evaluate it in the env environment, and return the result.
For the Environment
in most cases you could use
‘Environment.current()’. Before you start, you
need to initialize the global environment,
which you can do with
Environment.setCurrent(new Scheme().getEnvironment());
Alternatively, rather than setting the global environment, you can use this style:
Scheme scm = new Scheme(); Object x = scm.eval("(+ 3 2)"); System.out.println(x);
javax.script
portable Java scriptingKawa also supports the standard
javax.script
API.
The main advantage of this API is if you want your users to be able to choose
between multiple scripting languages. That way you can support Kawa
without Kawa-specific programming.
For example the standard JDK tool jrunscript provides a
read-eval-print-loop for any language that implements the javax.script
API. It knows nothing about Kawa but can still use it:
$ jrunscript -cp kawa.jar -l scheme scheme> (cadr '(3 4 5)) 4
(Of course the jrunscript
REPL isn’t as nice as the one that
Kawa provides. For example the latter can handle multi-line inputs.)
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