PLT Scheme v4.2.3

posted by Eli Barzilay

PLT Scheme version 4.2.3 is now available from http://plt-scheme.org/

• The unit test framework for the teaching languages provides check-member-of and check-range for checking “random functions”, i.e., “functions” that may produce several different results for one and the same argument.

• Added a new image library, 2htdp/image. Significant changes from htdp/image:

• copying and pasting does not introduce jaggies

• equal? comparisons are more efficient

• added rotation & scaling

• got rid of pinholes (new overlay, beside, above functions based on bounding boxes)

• The scheme/vector library provides common vector operations (also reprovided by scheme).

• The scheme/promise library provides several new kinds of promises with alternatives execution strategies.

• New port-reading utilities: in-port, port->list, file->list.

• A new require-macro, path-up, for requiring a file that is higher in the directory tree.