tricu (pronounced "tree-shoe") is a purely functional interpreted language implemented in Haskell. It is fundamentally based on the application of Tree Calculus terms, but minimal syntax sugar is included to provide a useful programming tool. tricu is under active development and you can expect breaking changes with nearly every commit.

tricu is the word for "tree" in Lojban: (x1) is a tree of species/cultivar (x2).

Features

Tree Calculus operator: t
Assignments: x = t t
Immutable definitions
Lambda abstraction syntax: id = (\a : a)
List, Number, and String literals: [(2) ("Hello")]
Function application: not (not false)
Higher order/first-class functions: map (\a : lconcat a "!") [("Hello")]
Intensionality blurs the distinction between functions and data (see REPL examples)
Simple module system for code organization

REPL examples

tricu < -- Anything after `--` on a single line is a comment
tricu < id = (\a : a) -- Lambda abstraction is eliminated to tree calculus terms
tricu < head (map (\i : lconcat i " world!") [("Hello, ")])
tricu > "Hello,  world!"
tricu < id (head (map (\i : lconcat i " world!") [("Hello, ")]))
tricu > "Hello,  world!"

tricu < -- Intensionality! We can inspect the structure of a function or data.
tricu < triage = (\a b c : t (t a b) c)
tricu < test = triage "Leaf" (\z : "Stem") (\a b : "Fork")
tricu < test (t t)
tricu > "Stem"
tricu < -- We can even convert a term back to source code (/demos/toSource.tri)
tricu < toSource not?
tricu > "(t (t (t t) (t t t)) (t t (t t t)))"
tricu < -- or calculate its size (/demos/size.tri)
tricu < size not?
tricu > 12

Installation and Use

Releases are available for Linux.

Or you can easily build and/or run this project using Nix.

Quick Start (REPL):
- nix run git+https://git.eversole.co/James/tricu
Build executable in ./result/bin:
- nix build git+https://git.eversole.co/James/tricu

./result/bin/tricu --help

tricu Evaluator and REPL

tricu [COMMAND] ... [OPTIONS]
  tricu: Exploring Tree Calculus

Common flags:
  -? --help       Display help message
  -V --version    Print version information

tricu [repl] [OPTIONS]
  Start interactive REPL

tricu eval [OPTIONS]
  Evaluate tricu and return the result of the final expression.

  -f --file=FILE  Input file path(s) for evaluation.
                    Defaults to stdin.
  -t --form=FORM  Optional output form: (tree|fsl|ast|ternary|ascii|decode).
                    Defaults to tricu-compatible `t` tree form.

tricu decode [OPTIONS]
  Decode a Tree Calculus value into a string representation.

  -f --file=FILE  Optional input file path to attempt decoding.
                    Defaults to stdin.

Acknowledgements

Tree Calculus was discovered by Barry Jay.

treecalcul.us is an excellent website with an intuitive Tree Calculus code playground created by Johannes Bader that introduced me to Tree Calculus.