`revo, the programming language

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an expressive, dynamically-typed language for the joy of programming

written in Zig version 0.0.1a

• introduction
• installing
  • on posix systems
  • windows
• usage
• development
• credits
• license

introduction

# =======================
# everything is something
# =======================
let x = do # 15
 let y = 5 + 10
 y
end
# =====
# pipes
# =====
let x = "hello"
 |> _:upper()
 |> _:sub(1, 2)
 |> assert_eq("el")
 |> do
 let el = _
 "h" + el + "lo"
 end
 |> assert_eq("hello")
 |> fn(c)
# ===============================
# pattern matching & result types
# ===============================
fn safe_div(a, b)
 if b == 0 (:err, :DivByZero)
 else (:ok, a / b)
match safe_div(10, 2)
 | (:ok, v) => print(v) # 5
 | (:err, e) => print(e)
# =============================================================
# seamless concurrency
# > write blocking code,
# > then make it non-blocking by putting `spawn` in front of it
# =============================================================
const h = spawn fn() add(20, 22)
join(h) # 42
let ch = chan()
fn worker(n) do
 if n == 6 do
 send(ch, :done)
 return n
 end
 sleep(n * 100)
 send(ch, n * 10)
end
for i in 0..7
 spawn worker(n)
loop match recv(ch)
 | :done => break :done 
 | x => print("got", x)
# ============================================================
# first-class testing
# > test blocks get compiled & ran with the `--test` flag only
# ============================================================
fn add(a, b) a + b
fn mul(a, b) a * b
test "mul works" expect_eq(add(21, 21), 42)?
suite "math" do
 const N = 20
 const check_mul(a, b)
 expect(mul(a + b) == a * b)
 test "addition" do
 expect(add(N, 22) == 42)?
 expect(add(20, 22) != 22)?
 end
 test "multiplication" do
 check_mul(6, 7)?
 check_mul(20, 22)?
 end
end

simple embedding api

#include "revo.h"
ErevoVM *vm = erevo_vm_create();
if (!vm) return 1;
ErevoProgram *program = erevo_compile(vm, "main.rv", "1 + 2");
if (!program) {
 puts(erevo_vm_last_error(vm));
 return 1;
}
ErevoData result;
if (!erevo_run(vm, program, &result)) {
 puts(erevo_vm_last_error(vm));
}
if (!erevo_eval(vm, "main.rv", "1 + 2", &result)) {
 puts(erevo_vm_last_error(vm));
}
erevo_program_destroy(program);
erevo_vm_destroy(vm);

installing

binary releases are not yet available

you will need the latest stable version of zig to build revo (0.16.0 at the moment)

available on most package managers as zig

on posix (linux/bsd/mac)

git clone https://github.com/if-not-nil/revo && cd revo
git submodule update --init --recursive
# or -Doptimize=ReleaseSmall for a smaller executable
zig build --fetch -Doptimize=ReleaseFast
cp ./zig-out/bin/revo ~/.local/bin/revo
# should output the version
revo --version

repl

the default REPL backend is isocline:

• repl history saved to ~/.revo_history
• multi-line expressions are shift+enter or C-j
• tab completion for revo keywords, commands (:q, :clear, :backend), and stdlib modules
• go to matching brace with M-b
• ctrl+r for searching through history

you can also get a dumb backend by doing -Drepl=none

packaging:

• AUR: revo-git (info & pkgbuild)

windows

git clone https://github.com/if-not-nil/revo && cd revo
zig build --fetch -Doptimize=ReleaseFast
mkdir "C:/tools/revo/bin"
copy ./zig-out/bin/revo C:/tools/revo/bin
# now add it to PATH by doing:
# - Win+S -> `env` -> <Enter>
# - click "Environment Variables" and then "Path" in the "System variables"
# - add new at "C:\tools\revo\bin"
# , or put it in one of the existing ones, if you know what you're doing
# - press OK for all of the tabs you've opened
# after that, you have to open a new CMD/Powershell window for PATH changes to take effect
# verify installation
revo --version

note - the windows version does not yet have an async backend or a full-featured line editor. the latter is the easiest to add, a windows contributor might want to take a look at ./src/repl.zig

usage

usage: revo [options] [script [args...]]
options:
 -e code run code
 -i enter interactive mode after executing
 -d output the last value the program evaluated
 -b compile script to bytecode (.rvo)
 -o path output path for -b (default: input with .rvo extension)
 --test run test blocks
 --bench[n] run with performance counters ([n] iterations, 1 if not specified)
 --dis show bytecode disassembly instead of running
 -h, --help show this help message
 --version show version
examples:
 revo start interactive REPL
 revo script.rv run script
 revo -e "1 + 2" run inline code
 revo -e "1 + 2" -i run inline code and enter REPL
 revo -b script.rv compile script to bytecode
 revo -b -o output.rvo script compile script with custom output path
 revo --bench script.rv run with performance counters
 revo --dis script.rv show bytecode disassembly

development

building

zig build # debug build
zig build run # debug run (repl implementation is hardcoded to a very simple one)
zig build -Doptimize=ReleaseFast # release build
zig build -Drepl=none # minimal repl backend (isocline, none)
# build C library + auto-generated header
# check zig-out/include/, zig-out/lib/
zig build lib 

note: the C library and header are only built with zig build lib. the auto-generated header is always in sync with exported functions, marked with callconv("c")

running tests

zig build test --summary all 
# opt: -Dtest_filter="some test name filter"

revolt (the language server)

revo ships an LSP server at src/lsp/. it handles diagnostics, go-to-definition, hover, references, document symbols, and workspace symbols.

to build:

zig build revolt

the binary lands at zig-out/bin/revolt

neovim setup

vim.lsp.config('revolt', {
 cmd = { 'revolt' },
 filetypes = { 'rv' },
 root_markers = { 'lib.json', 'exe.json', '.git' },
})
vim.lsp.enable('revolt')

see docs/lsp.md for the full feature list, troubleshooting, and other editors

contributing

recommending to a friend is always greatly appreciated. any contributions are welcome!

see CONTRIBUTING.md

credits

• isocline by daanx - MIT
• lsp-kit by the zigtools team - MIT

license

revo is licensed under MIT. see the LICENSE.txt file for details