scheme/demo/demo_std.scm · 5628 字节 · 下载原文

; demo_std.scm —— **第 1 层：标准输入输出**（Scheme 的 display / newline）

; demo_std.scm -- **layer 1: standard output** (Scheme's display / newline)

;

; 这一层就是语言自己的标准输出：往 stdout 写文本。

; This layer is just the language's own standard output: writing text to stdout.

; 也是最基础的一层，也是**唯一有逐字节确定性判据**的一层 —— 下面的输出

; It is also the most basic layer, and the **only one with a byte-for-byte deterministic criterion** -- the output below

; 跑两遍完全一样（不读输入、不用随机数、不看时间）。

; is identical on two runs (it reads no input, uses no random numbers and looks at no clock).

;

; ## 判据

; ## The criterion

;

;     vmlcli Examples/scheme/demo_std.scm

;

; 期望 stdout 逐字节等于本文件末尾「期望输出」那段。

; The expected stdout is byte-for-byte equal to the "expected output" block at the end of this file.

;

; ## ⚠ 本前端实测的五条限制（写 demo 时避开）

; ## ⚠ Five measured limitations of this frontend (avoid them when writing a demo)

;

;   · `display` / `print` **只取第一个实参、且不补换行** ⇒ 一行要用

;   · `display` / `print` **take only the first argument and add no newline** => one line must be built with

;     「若干次 `(display x)` + 一次 `(newline)`」拼出来。

;     "a few `(display x)` calls + one `(newline)`".

;   · **字符串字面量里没有任何转义** —— `SchemeCompiler/Lexer.cs` 的 `ReadString`

;   · **String literals contain no escapes at all** -- `ReadString` in `SchemeCompiler/Lexer.cs`

;     是「见到 `\` 就把反斜杠跳过、把下一个字符原样收下」⇒ `"\n"` 得到的是

;     is "on seeing a `\`, skip the backslash and take the next character verbatim" => `"\n"` yields

;     字母 `n`，`"\t"` 得到 `t`。所以本 demo 不写任何转义，

;     the letter `n`, and `"\t"` yields `t`. So this demo writes no escapes at all,

;     要换行一律用 `(newline)`。

;     and always uses `(newline)` for a line break.

;   · **`remainder` / `quotient` 在库里没有对应标签**（链接期报「未找到标签」）⇒

;   · **`remainder` / `quotient` have no matching labels in the library** (link time reports "label not found") =>

;     取模只好手算 `a - (a / b) * b`（本前端 `/` 就是整数除）。

;     modulo must be computed by hand as `a - (a / b) * b` (in this frontend `/` is integer division).

;   · `int->string` / `string->int` 这类名字**在本构建里链不到**（实测

;   · Names like `int->string` / `string->int` **cannot be linked in this build** (measured:

;     「未定义的函数 'int->string'」）⇒ 数字靠 `(display n)` 直接打。

;     "undefined function 'int->string'") => numbers are printed directly with `(display n)`.

;   · **用户函数里不能调库函数**（尾调用优化会跳过被调者的序言）⇒

;   · **A user function cannot call a library function** (tail-call optimization skips the callee's prologue) =>

;     本前端的所有调用都写在**顶层**，循环用 `do`（`let` 只在语句位受理）。

;     every call in this frontend is written at the **top level**, and loops use `do` (`let` is accepted only in statement position).

;

; 顶层的 `define` 都放在前面、`set!` 在顶层执行 —— 这条也照 catch.scm 的形态来。

; All top-level `define`s come first and `set!` runs at the top level -- this follows the shape of catch.scm as well.


(define lang (ui_scr_get_language))

(display "=== demo_std (Scheme) ===")
(newline)
(if lang (display "A plain string line") (display "纯字符串一行"))
(newline)

(define a 17)
(define b 25)

(display "a=")
(display a)
(display " b=")
(display b)
(newline)

(display "a+b=")
(display (+ a b))
(display " a-b=")
(display (- a b))
(display " a*b=")
(display (* a b))
(newline)

(display "a/b=")
(display (/ a b))
(display " a%b=")
(display (- a (* (/ a b) b)))
(newline)

(if lang (display "Negative numbers: ") (display "负数： "))
(display (- 0 a))
(display " ")
(display (- 0 (* a b)))
(newline)

; 循环算一个结果，证明这一层和语言本身是通的

; Compute one result in a loop, proving this layer and the language itself are wired up

(define total 0)
(do ((i 1 (+ i 1))) ((> i 10) 0)
    (set! total (+ total (* i i))))
(display "1^2+...+10^2 = ")
(display total)
(newline)

; 九九表的一小段（多行）

; A short stretch of the multiplication table (several lines)

(do ((i 1 (+ i 1))) ((> i 5) 0)
    (display i)
    (display " x 7 = ")
    (display (* i 7))
    (newline))

(if lang (display "=== Done ===") (display "=== 完成 ==="))
(newline)

; ── 期望输出（逐字节）────────────────────────────────────────────

; -- Expected output (byte-for-byte; each line below is printed in Chinese, and the line under it is its translation) --

; === demo_std (Scheme) ===

; 纯字符串一行

; A plain string line

; a=17 b=25

; a+b=42 a-b=-8 a*b=425

; a/b=0 a%b=17

; 负数： -17 -425

; Negative numbers: -17 -425

; 1^2+...+10^2 = 385

; 1 x 7 = 7

; 2 x 7 = 14

; 3 x 7 = 21

; 4 x 7 = 28

; 5 x 7 = 35

; === 完成 ===

; === Done ===

; ────────────────────────────────────────────────────────────────