flan/examples/core-input-keys.flan
Joseph Ferano afec482722 Ten raylib examples, and what they could not say
The first ten of raylib's core list, ported. Seven new bindings and the
named colour palette; nothing else was added, because a binding called
by nothing is the same as not having bound it.

The gaps they found are the point. No number reaches draw-text: i64->bytes
answers [u8], draw-text wants a string, and nothing bridges — five of the
ten wanted TextFormat and got a glyph table instead. And an enum parameter
cannot be driven by a loop variable: the index is an i32, the parameter is
an enum, neither converts, and a second declare-c with an i32 face is
refused because one C function gets one binding. Two correct rules that
compose into a wall.

None of the gaps expected blocked anything: no generics, no allocator, no
Vec, no escaping closure, no block-scoped defer. These are input-and-draw
programs over fixed-size state, which is the shape the language has.
2026-09-12 05:06:01 +07:00

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;;;; raylib [core] example - input keys
;;;;
;;;; examples/core/core_input_keys.c. Faithful, and the only thing worth noting
;;;; is a Flan rule rather than a raylib one.
;;;;
;;;; The C moves the ball by writing `ballPosition.x += 2.0f` on a local
;;;; struct. Flan has the same thing — a local IS an assignable place
;;;; (spec-memory.md) — but the local has to be a `defvar` here rather than a
;;;; `let` inside the loop, because a `let` binding is rebound every iteration
;;;; and the position has to survive between frames. The C's variable is
;;;; outside its while loop for the same reason; this is that, spelled with the
;;;; storage the language has.
;;;;
;;;; `(set (.x ball) ...)` works on a struct field of a global: a field of an
;;;; assignable place is itself one.
(import rl "vendor:raylib")
(defconst screen-width 800)
(defconst screen-height 450)
(defvar ball rl/Vector2)
(defn main []
(rl/init-window screen-width screen-height
"raylib [core] example - input keys")
(defer (rl/close-window))
(set ball (rl/Vector2 {:x (f32 (/ screen-width 2))
:y (f32 (/ screen-height 2))}))
(rl/set-target-fps 60)
(until (rl/window-should-close?)
;; Update. key-down? and not key-pressed?: this is meant to repeat for as
;; long as the key is held, which is the whole difference between the two.
(when (rl/key-down? :right) (set (.x ball) (+ (.x ball) 2.0)))
(when (rl/key-down? :left) (set (.x ball) (- (.x ball) 2.0)))
(when (rl/key-down? :up) (set (.y ball) (- (.y ball) 2.0)))
(when (rl/key-down? :down) (set (.y ball) (+ (.y ball) 2.0)))
;; Draw
(rl/begin-drawing)
(rl/clear-background rl/raywhite)
(rl/draw-text "move the ball with arrow keys" 10 10 20 rl/darkgray)
(rl/draw-circle-v ball 50.0 rl/maroon)
(rl/end-drawing)))