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## cond

Basis Function Combinator

This combinator works like a case statement. It expects a single quote
on the stack that must contain zero or more condition quotes and a
default quote. Each condition clause should contain a quoted predicate
followed by the function expression to run if that predicate returns
true. If no predicates return true the default function runs.

It works by rewriting into a chain of nested [ifte]{.title-ref}
expressions, e.g.:

    [[[B0] T0] [[B1] T1] [D]] cond
    -----------------------------------------
    [B0] [T0] [[B1] [T1] [D] ifte] ifte

Gentzen diagram.

### Definition

if not basis.

### Derivation

if not basis.

### Source

if basis

### Discussion

Lorem ipsum.

### Crosslinks

Lorem ipsum.