Getting Started

Building

Build-time requirements:

• gcc or clang
• standard C library + libm
• make
• For first-time libffi bootstrap: autoconf, automake, libtool, libtool-bin, libltdl-dev, pkg-config, m4, texinfo (Debian/Ubuntu names; equivalent on other distros). These are not needed once libffi/ has been built once.

Three submodules are vendored under the repo root: linenoise/ (REPL editing), mir/ (JIT backend), and libffi/ (FFI marshalling). All three are built statically and linked into the sel binary — no system runtime dependencies beyond libc.

git clone --recurse-submodules https://github.com/Luca00casati/sel.git
cd sel
make

If you already cloned without --recurse-submodules:

git submodule update --init

make produces a single sel binary. The standard library (core.sel) is a plain source file — sel loads it on demand via (load "core.sel"), so the working directory needs access to it.

Optional extras

• make raylib-binding regenerates gen_raylib.sel from /usr/include/raylib.h using genffi.py. Requires python-clang (libclang Python bindings) and raylib’s dev headers.

Running the REPL

Launch the interactive REPL by invoking sel with no arguments:

$ ./sel
sel repl  (ctrl+d to exit)
sel> (+ 1 2)
3
sel> (let x 10)
10
sel> (* x x)
100
sel>

The REPL is multi-line aware: if you open a parenthesis and press Enter without closing it, the prompt switches to ...> and keeps accumulating input until the expression is balanced.

sel> (let add
...>   (fn (a b) (+ a b)))
#<closure>
sel> (add 3 4)
7

Load the standard library explicitly when you need it:

sel> (load "core.sel")

After that, core macros and functions (map, filter, list3, etc.) are available.

State persists across expressions — bindings and functions defined with let and fn remain available for the rest of the session.

Exit the REPL with Ctrl+D (EOF).

Running a File

Pass one or more .sel files as arguments:

./sel program.sel
./sel lib.sel program.sel   # lib.sel is loaded first

All top-level expressions are evaluated in order across all files. The value of the last expression is printed as Result: <value>.

; hello.sel
(println "Hello, world!")
(+ 1 1)

$ ./sel hello.sel
Hello, world!
Result: 2

Flags

./sel --no-jit program.sel         # interpreter only, no JIT
./sel --dump-ast program.sel       # inspect parse tree
./sel --dump-inst program.sel      # inspect bytecode

First Program

; sum of 1..100
(let sum
  (fn sum (n acc)
    (if (= n 0)
      acc
      (sum (- n 1) (+ acc n)))))

(println (sum 100 0))

Save as sum.sel and run:

$ ./sel sum.sel
5050
Result: 5050