Plankalkül

Spec

Variables

V	parameters (r/o)
Z	temporaries (r/w)
R	results (w/o)

2D syntax 'sidebar'

In the 2D notation there is a vertical column on the right where the value of elements in that row is indicated:

 |Main Line
V|Variable Number
K|Component Number (Komponenten-Index
S|Comment Line (Struktur-Index)

So, as an example:

 |Z  ^ Z
V|4    2
K|2.3
S|0    0

(from page 8 in the Zuse PDF). This is (probably) equivalent to:

Z4[2.3] ^ Z2

in the linear notation.

Primitives

The only primitive type is boolean (or a bit). They are denoted by S0.

Arrays

Arrays can be made up of any other data type. For example:

8 X S0

is an array of 8 bits whereas:

n X 4 X S0

is an n-length array with each element being a 4-length array of bits.

Arrays can be subscripted:

 |V
V|0
K|1

means the 1st component of V0 (linear syntax is V0[1]).

Records

Page 2 of Bauer alludes to 'records' of the form (A2, A3). We need more info here.

Questions

• Are S (and maybe A) variables or types or constants or what? We know S0 is the boolean bit, S1 is an array of boolean bits and apparently S2 is a constant of some type.

• What is the difference between S and A?

• How is a function declared? The Bauer PDF gives this syntax:

P17 |R(V) => (R, R)
   V|  0      0  1
   S|  α      α  0

but.. how is this function called?, how do you actually define stuff to occur in the function, is the 'FIN' end symbol used?

• Are the S lines actually taken into account? Do they define the structure of the index?

Implementation

Is the 2d syntax representable in ascii in some obvious way? What are the advantages of the 2d syntax?