# Deforestation (computer science)

In the theory of programming languages in computer science, deforestation (also known as fusion) is a program transformation to eliminate intermediate lists or tree structures that are created and then immediately consumed by a program. The term "deforestation" was originally coined by Philip Wadler in his 1990 paper "Deforestation: transforming programs to eliminate trees".[1]

Deforestation is typically applied to programs in functional programming languages, particularly non-strict programming languages such as Haskell. One particular algorithm for deforestation, shortcut deforestation,[2] is implemented in the Glasgow Haskell Compiler.[3] Deforestation is closely related to escape analysis.