sutton037

The compiler development series of articles in The OCaml Journal have culminated in an example front-end compiler targetting HLVM that now supports variants and pattern matching in addition to previous features. These new language features have been implemented using only a few lines of code, bringing the front-end up to only 253 lines of OCaml code! This new functionality allows substantially more complicated ML-style programs to be written, including the following symbolic simplifier: # type expr = Int of int | Var of int | Add of expr * expr | M...

For around 30 years, the ML family of languages have been characterised by several unusual features including a novel and powerful higher-order module system. This language feature was pioneered by Dave MacQueen in the early 1980s and found its way into the Standard ML and OCaml languages. Higher-order modules allow one module to be parameterized over another module in the form of functors that map modules to modules. Higher-order modules turn out to be especially useful for parameterizing concrete data structures over more primitive data structures. Perhaps the most compelling application of higher-order modules comes from graph theory, where they allow algorithms over graphs to be abstracted over the concrete data structures used to represent the graphs. This application was discussed in our most recent OCaml Journal article " The A* algorithm " that describes a generalization of Dijkstra's shortest path algorithm that is widely used for route finding in game AI. Th...