posted by Eli Barzilay
PLT Scheme version 4.2.3 is now available from
The unit test framework for the teaching languages provides
check-rangefor 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
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)
scheme/vectorlibrary provides common vector operations (also reprovided by
scheme/promiselibrary provides several new kinds of promises with alternatives execution strategies.
New port-reading utilities:
A new require-macro,
path-up, for requiring a file that is higher in the directory tree.