Learn MERCURY with Real Code Examples

Mercury emphasizes declarative programming, separating logic from control flow.

It provides a strong static type system and mode system for arguments.

Mercury’s compiler optimizes for performance and guarantees no runtime type errors for well-typed programs.

Predicates and functions with explicit types

Modes defining input/output arguments

Determinism categories (det, semidet, nondet, multi)

Module system for code organization

Automatic memory management and garbage collection

Predicates (relations between terms)

Functions (deterministic computations)

Types (user-defined and built-in)

Modes (input/output specification)

Determinism declarations (det, semidet, multi, nondet)

Source files (.m)

Interface files (.m)

Modules for code organization

Test cases for predicates/functions

Documentation files

Write Mercury source file with predicates and functions

Specify types, modes, and determinism

Compile using Mercury compiler (mmc)

Test and debug using compiler feedback

Organize code into modules for maintainability

Beginner: simple deterministic predicates

Intermediate: multi and nondet predicates

Advanced: large module-based projects

Expert: symbolic computation or constraint systems

Mercury vs Prolog: stronger typing, mode and determinism system, better performance

Mercury vs Haskell: functional vs logic paradigm, Mercury is declarative logic

Mercury vs Python: specialized for logic, smaller ecosystem

Mercury vs Lisp: symbolic computation vs declarative logic

Mercury vs C: higher-level declarative logic, less low-level control

1995 – Mercury project started at University of Melbourne

1998 – First public release

2000s – Compiler optimizations and standard libraries expanded

2010s – Integration with C and Java via FFI improved

2025 – Latest stable release focusing on performance and tooling

Predicate: logical relation between terms

Function: deterministic computation

Mode: input/output argument specification

Determinism: guarantees about number of solutions

Module: code organization unit