Flatland

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The Flatland language operates on a 2D plane of instructions, but it is not grid-based (as opposed to Befunge and ><>). Rather, the execution paths are defined by geometric shapes, namely infinite lines and circles.

Inspired by ASCII-Only's chat message in PPCG.SE chat room:

possibly lines could be execution paths, and points and circles used to indicate control structures/literals. possibly

Synopsis

  • A program consists of a set of points, lines and circles.
  • Each point contains an instruction.
  • A line represents a sequential execution path.
  • A circle represents a loop.
  • There is one instruction pointer (IP), moving along the specified lines and circles.
  • An intersection represents a conditional; the IP transfers to another path if a certain condition is met.

Details

  • The language is stack-based, and the instruction set (likely) resembles one of Befunge or ><>, except the routing commands.
  • Points are defined by (x,y) coords.
  • Lines are defined by two points on it.
  • Circles are defined by its center and radius.
  • Point-on-line relationships are automatically detected with a tolerance value.
  • When the program starts, IP is at the first point specified, facing positive X direction (if ambiguous, positive Y).
  • The program terminates when the IP is on a line and no more points are left in the current direction.
  • On an intersection, the IP turns left if the top of the stack is negative, turns right if positive, and keeps moving in its current path if zero.
  • The following cases give undefined behavior (or forbidden, depending on implementation):
- No points or no paths are specified at all.
- The first point is not on any path.
- Two points in a program share the same position.
- A point in a program coincides with an intersection of two paths.
- Three or more paths intersect at the same position.
- Two paths are identical.

Instructions

TBD.

Syntax

TBD.

Turing-completeness

Although it is not proven yet, it is believed to be Turing-complete by reduction from Minsky machine given that the language has basic arithmetic (+-*/) instructions (looping and state transition are naturally represented by circles and intersections, respectively).