# Plankalkül

## Spec

### Variables

V | parameters (r/o) |

Z | temporaries (r/w) |

R | results (w/o) |

C | constants (?) |

Variables are initialized the first time they're assigned to, subsequent assignments are simply normal assignments.

### 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.

Note: not quite sure what the operator means yet, possibly greater-than.

### 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.

### Operators

Note that this list is vastly incomplete.

= | Equality test |

=> | Assignment |

+ | Addition |

- | Subtraction (inferred, may not exist) |

### The µ operator

µx(x ∈ V ^ R(x)) 0

Apparently this means 'The next element of V0 for which the procedure call R returns true'.

### Conditionals

Conditionals are of the form *expression* -> *statement*. There is no else clause. There is also no 'or' for the expression.

### Loops

Loops are initiated using the letter W. I don't really understand anything beyond that.

## 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?

## Links

- The Life and Work of Konrad Zuse (by Horst Zuse) Part 5: Konrad Zuse's Plankakül Programming Language (1942-1945/6)
- Konrad Zuse Internet Archive

## Notes

I'm looking through my character map for some useful HTML entities:

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