flan/examples/text-input-box.flan
Joseph Ferano a4c6b996ff def re-runs its initialiser, and defvar is renamed defonce
The trio the author decided on 2026-09-20 is now all built: def is CL's
defparameter — its initialiser runs on every daemon re-run, unguarded, so
an edited initialiser repaints the same storage on C-c C-c plus re-run —
defonce (Clojure's name for CL's defvar, per the author) initialises once
behind the .init~once. flag, and defconst stays the image.

One parse arm reads both forms; the difference is Ast.reinit, carried to
Tast.global's grerun. Emit.startup_plan gives a def no guard flag, and
Check.check_global lifts every def initialiser — zero and literal
included — into global/<n>, so the host's startup reaches it through the
function cell and a re-evaluated def swaps it (Session's def_inits;
Emit.redefinition declares the cell for a non-sibling target). The old
defvar spelling is refused with the rename and both compiling spellings,
and every program, test, doc and editor list is swept — except sand.flan,
the author's live WIP, whose seven defvar lines are flagged in FIX.org
and keep its three dependent tests red on this branch.
2026-09-21 07:12:04 +07:00

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;;;; raylib [text] example - input box
;;;;
;;;; examples/text/text_input_box.c. Two things in this file exist nowhere
;;;; else in the corpus.
;;;;
;;;; The first is get-char-pressed. Everything ported so far reads input as
;;;; state — key-down?, key-pressed?, the mouse position — and this is the
;;;; only example that drains a *queue*: raylib buffers the characters the
;;;; platform produced since the last frame, already through the keyboard
;;;; layout and the dead keys, and hands them back one at a time until it is
;;;; empty. The loop that empties it is the point of the example, and a
;;;; program that read the queue once per frame instead would silently drop
;;;; the second character of a fast pair.
;;;;
;;;; raylib says "empty" by answering 0, and rl/get-char-pressed is now a
;;;; Flan wrapper that says it with None instead — see raylib.flan, "Draining
;;;; raylib's two input queues". What that buys is visible below: the C
;;;; shape, which this file had, reads the queue in *two* places, once to
;;;; prime the loop and once at the bottom of the body, and a `> 0` in
;;;; between that a reader has to know raylib's convention to trust. The
;;;; Option shape reads it in one place, and the case where there is no
;;;; character is a branch the checker knows about rather than a comparison.
;;;;
;;;; The second is set-mouse-cursor, which needed a new defenum. raylib's
;;;; header says `int cursor` and means one of eleven MOUSE_CURSOR_ values, so
;;;; the Flan face is `MouseCursor` — hand-written in raylib.flan beside the
;;;; other cursor calls, excluded from the generated half, and mapped in
;;;; `bindings` so the eleven members are checked against the header. See the
;;;; comment there: this call is made on every frame off a hover test, and the
;;;; failure an i32 would allow is not a crash but a pointer in the wrong
;;;; shape, which nothing reports.
;;;;
;;;; The text buffer, and what it says about strings. The C keeps a
;;;; `char name[MAX_INPUT_CHARS + 1]` and maintains the NUL itself; here it is
;;;; a `[9 u8]` with no terminator, and every use is `(string (slice name 0
;;;; letter-count))`. A Flan string is a pointer and a length, and the shim
;;;; that calls DrawText copies it and NUL-terminates the copy
;;;; (lib/shim.ml) — so the extra byte the C needs has no counterpart here and
;;;; the buffer is exactly as long as the characters it can hold. The two
;;;; draws and the measure all take the same slice, so they cannot disagree
;;;; about where the text ends.
;;;;
;;;; Dropped from the C: its IsAnyKeyPressed helper, which is defined at the
;;;; bottom of the file and called from nowhere.
(import rl "vendor:raylib")
(import d "digits.flan")
(defconst screen-width 800)
(defconst screen-height 450)
(defconst max-input-chars 9)
;; No +1: see the header comment. There is no NUL to leave room for.
(defonce name [9 u8])
(defonce letter-count i32)
(defonce text-box rl/Rectangle)
(defonce mouse-on-text bool)
(defonce frames-counter i32)
(defn main [] ()
(rl/init-window screen-width screen-height
"raylib [text] example - input box")
(defer (rl/close-window))
(set name (array max-input-chars u8))
(set letter-count 0)
(set text-box (rl/Rectangle {.x (- (/ (f32 screen-width) 2.0) 100.0)
.y 180.0 .width 225.0 .height 50.0}))
(set mouse-on-text false)
(set frames-counter 0)
(rl/set-target-fps 60)
(until (rl/window-should-close?)
;; Update
(set mouse-on-text
(rl/collision-point-rec? (rl/get-mouse-position) text-box))
(if mouse-on-text
(do
(rl/set-mouse-cursor :ibeam)
;; Drain the character queue: more than one character can arrive in
;; a single frame — holding a key with the platform's repeat on is
;; the ordinary way that happens — and None is the end of it.
(let [draining true]
(while draining
(match (rl/get-char-pressed)
None (set draining false)
;; 32..125 is the printable ASCII range the C accepts. Anything
;; outside it — an accented letter, a control character — is
;; dropped rather than stored, because the buffer is bytes and a
;; codepoint above 127 would need more than one of them.
(Some key)
(when (and (>= key 32) (<= key 125)
(< letter-count max-input-chars))
(set (at name letter-count) (u8 key))
(set letter-count (+ letter-count 1))))))
(when (rl/key-pressed? :key-backspace)
(set letter-count (- letter-count 1))
(when (< letter-count 0) (set letter-count 0))))
(rl/set-mouse-cursor :default))
;; The blink phase only runs while the box has focus, so the underscore is
;; always visible on the frame the pointer arrives.
(if mouse-on-text
(set frames-counter (+ frames-counter 1))
(set frames-counter 0))
;; Draw
(rl/with-drawing
(rl/clear-background rl/raywhite)
(rl/draw-text "PLACE MOUSE OVER INPUT BOX!" 240 140 20 rl/gray)
(rl/draw-rectangle-rec text-box rl/lightgray)
(rl/draw-rectangle-lines (i32 (.x text-box)) (i32 (.y text-box))
(i32 (.width text-box)) (i32 (.height text-box))
(if mouse-on-text rl/red rl/darkgray))
(let [typed (string (slice name 0 letter-count))]
(rl/draw-text typed (+ (i32 (.x text-box)) 5) (+ (i32 (.y text-box)) 8)
40 rl/maroon)
;; The C's TextFormat("INPUT CHARS: %i/%i", ...), reassembled out of
;; examples/digits.flan the way the other ports do it. `typed` is a view
;; of `name` and not of the runtime's shared format buffer, so it
;; survives the two numbers being formatted — which a value from
;; i64->bytes would not.
(let [x 315]
(set x (+ x (d/draw-piece "INPUT CHARS: " x 250 20 rl/darkgray)))
(set x (+ x (d/draw-int letter-count x 250 20 rl/darkgray)))
(set x (+ x (d/draw-piece "/" x 250 20 rl/darkgray)))
(d/draw-int max-input-chars x 250 20 rl/darkgray))
(when mouse-on-text
(if (< letter-count max-input-chars)
;; Twenty frames on, twenty frames off, at the pen position after
;; whatever has been typed.
(when (= (% (/ frames-counter 20) 2) 0)
(rl/draw-text "_"
(+ (i32 (.x text-box)) 8 (rl/measure-text typed 40))
(+ (i32 (.y text-box)) 12) 40 rl/maroon))
(rl/draw-text "Press BACKSPACE to delete chars..." 230 300 20
rl/gray)))))))