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Usage: scm2java [-p constant ] file1.scm file2.scm ...
Usage: scm2java [-p constant ] file1.scm file2.scm ... dir/
  Translates Scheme files file1.scm, file2.scm, ... to
  dir/ and dir/Filen.txi.

Source Language

Scm2java is a Scheme to Java translator for a subset of Scheme. Using Scheme files as source, scm2java produces texinfo documentation and formatted Java code preserving comments; and type, function, and variable names as much as possible. The output from scm2java is human-readable and can form the base for further development in Java; abandoning the original Scheme source.

Scope of the Scheme Subset

The Scheme subset supported by scm2java is listed at Subset.

Scheme integers and real numbers, booleans, chars, and strings are translated to the equivalent Java types. SLIB byte vectors map to the type byte[] in Java code. Vectors of user defined (Java) types are supported.

The user incorporates custom Java data types by coding their definitions and accessors in a Java source file. For the purposes of running in Scheme, put analogous definitions in a file which is not translated by scm2java.

Characters in variable names are translated as follows:
`%' => `_Percent'
`@' => `_At'
`->' => `To'
`=' => `Equal'
`>' => `More'
`<' => `Less'
`?' => `_P'
`:' => `_'
`-' => `'

Scm2java does not include support for a Scheme runtime. Generated Java programs should not assume general Scheme values unless linked with a library providing these features.

Scheme identifier names are used to determine the Java types of the corresponding variables and methods.


Defmacros transforming Scheme code to Scheme code may be defined in Scheme source files. If there are defmacros used in more than one Scheme source file, they can be removed to a separate file, and that file imported by a call to defmacro:load in each file (before a defmacro is invoked).

Function: defmacro:load filename

Imports defmacros from filename.

Variable: *schlep-defmacros*

Is an alist associating defmacro names with their transformers. It is fluid-let during each file translatation, so that scm2java macro definitions do not take effect in the Scheme top level.


Variable: declarations
The Java types to which variables are translated are controlled by declarations. A declaration is a list (glob type). glob is a match string; type an expression. Globs are matched to variable names with trailing digits removed. Declarations made later override those made earlier.

Declarations can be made by a call to declare-names. If no declarations have been made before schlep is called, schlep will read a list of declarations from a file named `schlep.typ' if it exists in the same directory as the Scheme file being translated.

If the type is a symbol or string, variables which match the glob string will be declared as types of that name. If the type is a list, then it will be interpreted as follows.

(ptr type)
produces * type.
(array type)
produces type[].

Types can be nested. Procedure names ending with `!' are typed to return void. Procedure names ending with `?' are translated to names with a trailing `_P'.

These procedures can be mixed with code to be translated.

Function: declare-names globs
globs must be a list of lists (declarations). Glob declarations may have local scope. Glob declarations at top level persist from one file to the next.

The Scheme files in the table at
have examples of the use of declare-names.

Target Language

Function: string ...
In Scheme source, has no effect, but the strings are written to during translation.

Variable: number-lines?

Define number-lines? to #t for Java code to be prefixed with commmented line numbers. The default value is #f.

Schlep API

The following procedures are called to translate a file. They should not be called from the file being translated.

Function: schlep filename ...
Translates scheme files to Java. Each argument must be a string. If the suffix is:
Produces files and Filename.txi (Filename is capitalized).

If filename.txi is empty after translation, then it is deleted.

Procedure: declarations-report! cumulative? port
Prints an association-list (suitable passing to declare-name!) along with the counts of references to each name pattern type declared.

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