APL concepts in Smalltalk

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APL concepts in Smalltalk

Apl is an Array processing language. See Wikipedia article about APL

The concepts of APL are:

data is either scalar or a vector with a shape (dimensions)
- two basic data types: numbers and characters
functions operate on one or two data elements

You learn to think in shaped vectors and a mathematical way to manipulate data.

I use the microApl Community Edition, which is available for Linux.

Smalltalk is a nice, small and concise language. See Wikipedia article about Smalltalk

It has two concepts:

everything is an object
- no other data type
objects communicate through messages

You learn to think in objects and models.

I use Pharo, which is available for Linux, Windows and Mac.

More languages with clean concepts are: Prolog, Lisp, XSLT and other.

The AplLike implementation

I am a big fan of Smalltalk. The Smalltalk collection framwork is very matured.
Shaped Vectors, as in APL, is a thing I was missing in Smalltalk.

So I started to reimplement using reverse engineering the APL functions and vectors in Smalltalk. This resulted in the AplLike package.

Have a look at:

the implemented functions so far.
the Monticello information for downloading the AplLike package in pharo
two small Examples with APL and Smalltalk code
some Differences justified by the different evaluation order of APL and Smalltalk.
some Screenshots.

The next step - smalltalk like integration

The next step is to make the underlying principles more Ssmalltalk-like, i.e. trying to integrate them in the famous Smalltalk collection framwork.

So the new classes will be:

ShapedArray (derivated from Array). The class with the APL inspired interface.
ShapedScalar (derivated from ShapedArray). Special handling if there is an empty shape.
ShapedScalarBasic (derivated from ShapedScalar). Encapsulates Smalltalk objects
ArrayShape (derivated from Array). A class describing the shape of a ShapedArray.

Things to cover

APLs representation of true/false as 1/0 (AplTrue/AplFalse)
naming of methods
categorizing of methods
sequence of axis
Error handling

Contact

mailto:kontakt@florian-greese.de