Joseph Ferano
421e09e0d6
(string b) is the mirror of (bytes s) and costs nothing: emit.ml already
lowers Types.String and Types.Slice _ to the same %slice, 16 bytes at
align 8, so a string and a [u8] are the identical value at run time and
both directions emit as the argument itself. What changes is only what
the checker will let the value be passed to — which was the whole gap.
Two decisions, both written into check.ml's comment.
It does not check UTF-8, because `string` does not claim UTF-8. The
prelude settles it: valid-utf8? is an ordinary function you call when you
care, decode-rune / rune-at / rune-count all take [u8] and not string,
and decode-rune answers {:ok false :width 1} on a malformed byte rather
than assuming well-formed input. The one place the runtime treats a
string differently from a byte slice is flan_escape_bytes, for a string
nested in a printed structure, and that is a byte-wise escape table with
no decoding in it. A check here would be the only enforcement point in
the language, which is a claim the rest of it does not make.
It does not widen the literal-write hole. That hole is the other
direction — (bytes "Hi") hands back a writable-looking slice over
constant data — and this direction only loses the ability to write, so
the result reaches strictly fewer stores than its argument could.
Provenance is still what the other direction needs; nothing here waits
on it.
The one sharp edge is not new but is easier to trip over now, and is
recorded in both the checker and digits.flan: i64->bytes, f64->bytes and
u64->bytes all view the same static buffer in the runtime, overwritten
by the next call, and calling it a string does not copy it. Format, draw,
then format the next one.
examples/digits.flan keeps its three signatures and loses its middle: the
[10 string] table, the per-glyph pen and the digit arithmetic are gone,
and draw-int is one draw-text. What survives is the part (string ...)
does not answer — i64->bytes has no field width, so "%03i" is still
assembled, and f64->bytes is "%g", so fixed decimal places are still a
split into two integers. core-input-multitouch and
core-input-virtual-controls ignored the width they were given, so both
inline the draw and stop importing digits.flan entirely.
test/programs/string-of-bytes.flan at -O2 and -O0: a number round-tripped,
an empty slice, sub-views whose length is not the underlying storage's,
and the result across a declare-c boundary. The last is the one that
could have been wrong — "hello world" cut to five bytes has a space where
C wants a NUL, so a shim that trusted the bytes would print all eleven.
120 lines
4.9 KiB
Plaintext
120 lines
4.9 KiB
Plaintext
;;;; raylib [core] example - delta time
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;;;;
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;;;; examples/core/core_delta_time.c. Needed get-mouse-wheel-move and get-fps,
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;;;; both now bound — draw-fps was already there, but it puts the number on the
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;;;; screen itself and this example wants to compare it against the target it
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;;;; set, so it needs the number back.
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;;;;
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;;;; Three TextFormats in the C. Two of the three are a fixed number of
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;;;; decimal places, which `f64->bytes` cannot do — it is "%g" — so they
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;;;; still go through examples/digits.flan. The integer one does too, only
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;;;; because its width is needed to put the next piece after it; the draw
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;;;; itself is now (string (i64->bytes n)) and one draw-text.
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;;;;
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;;;; One faithfulness note that is a bug in the C and is kept anyway: it draws
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;;;; `TextFormat("Frame time: %02.02f ms", GetFrameTime())` — GetFrameTime is
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;;;; in SECONDS, so at 60 fps the C's own screen reads "0.02 ms" for what is
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;;;; really 16.7 ms. Porting it as-is means the two programs show the same
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;;;; thing, which is what a port is for; the milliseconds are drawn beside it
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;;;; here rather than instead of it, so the file is not quietly asserting that
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;;;; the original was right.
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;;;;
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;;;; The two circle positions are `defvar`s for the usual reason: they are
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;;;; state between frames and a `let` inside the loop would reset them.
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(import rl "vendor:raylib")
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(import d "digits.flan")
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(defconst screen-width 800)
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(defconst screen-height 450)
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(defconst speed f32 10.0)
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(defconst circle-radius f32 32.0)
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(defvar delta-circle rl/Vector2)
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(defvar frame-circle rl/Vector2)
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(defvar current-fps i32)
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(defn main []
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(rl/init-window screen-width screen-height
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"raylib [core] example - delta time")
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(defer (rl/close-window))
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(set current-fps 60)
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(set delta-circle (rl/Vector2 {:x 0.0 :y (/ (f32 screen-height) 3.0)}))
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(set frame-circle (rl/Vector2 {:x 0.0
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:y (* (f32 screen-height) (/ 2.0 3.0))}))
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(rl/set-target-fps current-fps)
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(until (rl/window-should-close?)
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;; Update
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(let [wheel (rl/get-mouse-wheel-move)]
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(unless (= wheel 0.0)
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(set current-fps (+ current-fps (i32 wheel)))
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(when (< current-fps 0) (set current-fps 0))
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(rl/set-target-fps current-fps)))
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;; The whole point of the example: one circle is scaled by the frame time
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;; and one is not, so lowering the target with the wheel makes the second
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;; one crawl while the first keeps its speed.
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(set (.x delta-circle)
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(+ (.x delta-circle) (* (rl/get-frame-time) (* 6.0 speed))))
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(set (.x frame-circle) (+ (.x frame-circle) (* 0.1 speed)))
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(when (> (.x delta-circle) (f32 screen-width)) (set (.x delta-circle) 0.0))
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(when (> (.x frame-circle) (f32 screen-width)) (set (.x frame-circle) 0.0))
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(when (rl/key-pressed? :r)
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(set (.x delta-circle) 0.0)
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(set (.x frame-circle) 0.0))
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;; Draw
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(rl/begin-drawing)
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(rl/clear-background rl/raywhite)
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(rl/draw-circle-v delta-circle circle-radius rl/red)
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(rl/draw-circle-v frame-circle circle-radius rl/blue)
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;; "FPS: unlimited (%i)" when the target is 0, "FPS: %i (target: %i)"
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;; otherwise — the C's own branch, reassembled out of literals and
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;; draw-int. `x` walks along the line as each piece is drawn, which is what
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;; the returned width from draw-int is for.
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(if (<= current-fps 0)
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(let [x 10]
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(rl/draw-text "FPS: unlimited (" x 10 20 rl/darkgray)
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(set x (+ x (rl/measure-text "FPS: unlimited (" 20)))
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(set x (+ x (d/draw-int (rl/get-fps) x 10 20 rl/darkgray)))
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(rl/draw-text ")" x 10 20 rl/darkgray))
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(let [x 10]
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(rl/draw-text "FPS: " x 10 20 rl/darkgray)
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(set x (+ x (rl/measure-text "FPS: " 20)))
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(set x (+ x (d/draw-int (rl/get-fps) x 10 20 rl/darkgray)))
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(rl/draw-text " (target: " x 10 20 rl/darkgray)
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(set x (+ x (rl/measure-text " (target: " 20)))
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(set x (+ x (d/draw-int current-fps x 10 20 rl/darkgray)))
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(rl/draw-text ")" x 10 20 rl/darkgray)))
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;; The C's line, kept exactly — seconds, labelled ms.
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(let [x 10]
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(rl/draw-text "Frame time: " x 30 20 rl/darkgray)
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(set x (+ x (rl/measure-text "Frame time: " 20)))
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(set x (+ x (d/draw-f32 (rl/get-frame-time) 2 x 30 20 rl/darkgray)))
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(rl/draw-text " ms" x 30 20 rl/darkgray))
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;; And the same number in the unit the label claims, so the file does not
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;; have to be read to notice.
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(let [x 10]
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(rl/draw-text "(really " x 50 20 rl/lightgray)
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(set x (+ x (rl/measure-text "(really " 20)))
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(set x (+ x (d/draw-f32 (* (rl/get-frame-time) 1000.0) 2 x 50 20
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rl/lightgray)))
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(rl/draw-text " ms)" x 50 20 rl/lightgray))
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(rl/draw-text "Use the scroll wheel to change the fps limit, r to reset"
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10 70 20 rl/darkgray)
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(rl/draw-text "FUNC: x += GetFrameTime()*speed" 10 110 20 rl/red)
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(rl/draw-text "FUNC: x += speed" 10 260 20 rl/blue)
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(rl/end-drawing)))
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