flan/examples/core-input-mouse.flan
Joseph Ferano 26c53e0a19 Every defn in the tree states its return type, and Unit is written ()
The mechanical half, ahead of the parser change that needs it. tools/unit-return.py
fills the empty slot with () and rewrites Unit as () wherever a type is spelled --
(Fn [i32] Unit), (Map i32 Unit), a return type written out.

Deciding whether a defn already had a return type is the whole difficulty, and
the script does it the way parse.ml did: is_type_form is transcribed rather than
improved, because being identical to the parser it replaces is what makes the
sweep meaning-preserving. It is re-runnable, so the lanes that branched before
this can have the same pass at merge:

    python3 tools/unit-return.py .
    python3 tools/unit-return.py --in-strings test/test_flan.ml test/test_acceptance.ml \
        test/test_session.ml emacs/test-flan-dev.el emacs/test-flan-mode.el
    python3 tools/unit-return.py --raw-ml lib/prelude.ml
    python3 tools/unit-return.py --in-html web/index.html

-v logs every defn it saw and what it decided, which is how a sweep of 440 sites
gets reviewed at all. Embedded modes pool a file's type declarations across all
its fragments, because a snippet split across concatenation -- decls ^ "(defn f
[s [u8]] Cursor ...)" -- cannot see the names the other half declared; pooled
names count only in bare-symbol position, for the same reason the prelude's do.
A fragment that cuts off mid-form is skipped rather than guessed at. Five sites
in test_flan.ml still needed a hand, and they are in this commit.

Two things ride along because the sweep needs them: parse.ml reads a lone () as
the return type of a function with no body, which was not a shape the old
optional slot could produce; and the map refusals name () rather than Unit, since
that is now the spelling a caller wrote.
2026-09-12 23:06:40 +07:00

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;;;; raylib [core] example - input mouse
;;;;
;;;; examples/core/core_input_mouse.c. Needed three new bindings — show-cursor,
;;;; hide-cursor and cursor-hidden? — which are now in vendor/raylib.
;;;;
;;;; The C's `else if` chain over the seven mouse buttons is a `cond` here.
;;;; That is not a workaround: `cond` is what Flan has and it is the same
;;;; first-match-wins shape, with `:else` where C falls off the end. The order
;;;; matters in both — two buttons pressed on the same frame give the earlier
;;;; one, which is the C's behaviour and not an accident of the port.
;;;;
;;;; The colour has to be a `defvar` rather than a `let`, for the reason
;;;; core-input-keys' position does: it is state between frames.
(import rl "vendor:raylib")
(defconst screen-width 800)
(defconst screen-height 450)
(defvar ball-color rl/Color)
(defn main [] ()
(rl/init-window screen-width screen-height
"raylib [core] example - input mouse")
(defer (rl/close-window))
;; The C also initialises the ball's POSITION, to {-100,-100} so it starts
;; off-screen. That is dead there and is not here: the first thing the loop
;; does is overwrite it with get-mouse-position, before anything is drawn.
(set ball-color rl/darkblue)
(rl/set-target-fps 60)
(until (rl/window-should-close?)
;; Update
(when (rl/key-pressed? :h)
(if (rl/cursor-hidden?) (rl/show-cursor) (rl/hide-cursor)))
(let [ball (rl/get-mouse-position)]
(set ball-color
(cond
(rl/mouse-button-pressed? :left) rl/maroon
(rl/mouse-button-pressed? :middle) rl/lime
(rl/mouse-button-pressed? :right) rl/darkblue
(rl/mouse-button-pressed? :side) rl/purple
(rl/mouse-button-pressed? :extra) rl/yellow
(rl/mouse-button-pressed? :forward) rl/orange
(rl/mouse-button-pressed? :back) rl/beige
:else ball-color))
;; Draw
(rl/begin-drawing)
(rl/clear-background rl/raywhite)
(rl/draw-circle-v ball 40.0 ball-color)
(rl/draw-text "move ball with mouse and click mouse button to change color"
10 10 20 rl/darkgray)
(rl/draw-text "Press 'H' to toggle cursor visibility" 10 30 20 rl/darkgray)
(if (rl/cursor-hidden?)
(rl/draw-text "CURSOR HIDDEN" 20 60 20 rl/red)
(rl/draw-text "CURSOR VISIBLE" 20 60 20 rl/lime))
(rl/end-drawing))))