Module var

A higher-level interface for building lax Open Hypergraphs, including helpers to use rust operators like +, &, etc. to build terms. Here’s an example of using this interface to build a “full adder” circuit.

fn full_adder(a: Var, b: Var, cin: Var) -> (Var, Var) {
   let a_xor_b = a.clone() ^ b.clone();
   let a_and_b = a & b;

   (a_xor_b, a_and_b)
}

This constructs a crate::lax::OpenHypergraph like the one below, where dashed lines indicate nodes connected by the quotient map.

    ┌──────┐             ┌──────┐
a   │      ├───●╌╌╌╌╌●───┤      │    a ^ b
●───┤ Var  │             │ XOR  ├───●
    │      ├───●     ●───┤      │
    └──────┘    \   /    └──────┘
                 \ /
                  X
                 / \
    ┌──────┐    /   \    ┌──────┐
b   │      ├───●     ●───┤      │    a & b
●───┤ Var  │             │ AND  ├───●
    │      ├───●╌╌╌╌╌●───┤      │
    └──────┘   x1    y1  └──────┘

The purpose of a Var is to explicitly track variable usage: each time the var is used in an expression, a new node is created in the underlying OpenHypergraph, representing a copy. Note however that a Var correponds to a hyperedge rather than a node.

See examples/adder.rs for a comprehensive example, including a definition of a simple language of simple digital circuits.

Structs

Var

Traits

HasAdd

Vars can be added when the underlying signature has an operation for ‘addition’.

HasBitAnd

Vars support this operator when the underlying signature has the appropriate operation.

HasBitOr

Vars support this operator when the underlying signature has the appropriate operation.

HasBitXor

Vars can be added when the underlying signature has an operation for ‘addition’.

HasDiv

Vars support this operator when the underlying signature has the appropriate operation.

HasMul

Vars support this operator when the underlying signature has the appropriate operation.

HasNeg

Vars support this unary operator when the underlying signature has the appropriate operation.

HasNot

Vars support this unary operator when the underlying signature has the appropriate operation.

HasShl

Vars support this operator when the underlying signature has the appropriate operation.

HasShr

Vars support this operator when the underlying signature has the appropriate operation.

HasSub

Vars support this operator when the underlying signature has the appropriate operation.

HasVar

Functions

operation

A general helper for constructing n → 1 maps