Compiler.Hoopl.Zipper

Documentation

data ZBlock n e x where

Constructors

ZFirst :: n C O -> ZBlock n C O

ZMiddle :: n O O -> ZBlock n O O

ZLast :: n O C -> ZBlock n O C

ZCat :: ZBlock n O O -> ZBlock n O O -> ZBlock n O O

ZHead :: ZBlock n C O -> n O O -> ZBlock n C O

ZTail :: n O O -> ZBlock n O C -> ZBlock n O C

ZClosed :: ZBlock n C O -> ZBlock n O C -> ZBlock n C C

Instances

Edges n => Edges (ZBlock n)

type ZGraph = Graph' ZBlock

type ZBody = Body' ZBlock

frontBiasBlock :: ZBlock n e x -> ZBlock n e x

A block is front biased if the left child of every concatenation operation is a node, not a general block; a front-biased block is analogous to an ordinary list. If a block is front-biased, then its nodes can be traversed from front to back without general recusion; tail recursion suffices. Not all shapes can be front-biased; a closed/open block is inherently back-biased.

backBiasBlock :: ZBlock n e x -> ZBlock n e x

A block is back biased if the right child of every concatenation operation is a node, not a general block; a back-biased block is analogous to a snoc-list. If a block is back-biased, then its nodes can be traversed from back to back without general recusion; tail recursion suffices. Not all shapes can be back-biased; an open/closed block is inherently front-biased.