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GoldfishScheme.tmu
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<TMU|<tuple|1.1.0|2025.0.3>>
<style|<tuple|book|chinese|literate|goldfish|reduced-margins|guile|smart-ref|preview-ref|python|elvish>>
<\body>
<\hide-preamble>
<assign|scm|<macro|body|<goldfish-lang|<arg|body>>>>
<assign|scm-chunk|<\macro|name|prev|next|body>
<\generic-chunk|<arg|name>|<arg|prev>|<arg|next>>
<with|mode|prog|prog-language|goldfish|font-family|rm|<arg|body>>
</generic-chunk>
</macro>>
<assign|subparagraph|<macro|title|<assign|subparagraph-numbered|<compound|subparagraph-display-numbers>><assign|subparagraph-prefix|<macro|<compound|the-subparagraph>.>><compound|next-subparagraph><compound|subparagraph-clean><compound|subparagraph-header|<arg|title>><compound|subparagraph-toc|<arg|title>><small|<if|<value|subparagraph-numbered>|<compound|subparagraph-numbered-title|<arg|title>>|<compound|subparagraph-unnumbered-title|<arg|title>>>>>>
<assign|r7rs|<flag|R7RS|dark cyan>>
<assign|srfi|<flag|SRFI|dark red>>
<assign|goldfish-version|17.11.0>
<assign|typehint|<macro|body|<goldfish-lang|<arg|body>>>>
<assign|font|math=Latin Modern Math,cjk=Noto CJK SC,CMU>
</hide-preamble>
<chapter|Goldfish Scheme简介>
\;
Goldfish Scheme，又称金鱼Scheme，是<hlink|三鲤网络|https://liiistem.cn/>发起的Scheme解释器实现。
Goldfish Scheme解释器具有以下特性：
<\itemize>
<item>兼容R7RS small标准
<item>提供类似Python的标准库
<item>小巧且快速
</itemize>
<section|背景>
Goldfish Scheme创建之初的目的是为了服务墨干理工套件及其商业版Liii STEM。
墨干一开始使用的是S7 Scheme，然而S7 Scheme并不严格遵循R7RS small标准，也没有提供常见的SRFI实现。故而我们决定在S7 Scheme的基础上，发布Goldfish Scheme，更加严格地遵循R7RS small标准，并提供常见的SRFI实现作为Goldfish Scheme的内置标准库。另外，无论是R7RS small还是SRFI都没有提供同时兼容macOS, GNU/Linux和Windows的类似于Python的os模块的标准库，故而我们模仿了Python的os模块，实现金鱼的内置标准库<scm|(liii os)>，以提供<scm|listdir>、<scm|mkdir>等常见功能。
<section|文学编程>
Goldfish Scheme最初的三位作者是沈达、刘念和Yansong Li，项目立项时就是采用文学编程的方式实现Goldfish Scheme的Scheme部分。
一开始，我们的文学编程文档<shell|Goldfish.tmu>是不开源的，我们只开源了Goldfish Scheme的代码，其中代码是几乎没有任何注释的，因为我们在文学编程文档中的代码块之外会撰写注释。后来来自Emacs China社区的StarSugar开始向Goldfish Scheme项目贡献代码，于是我们决定将Goldfish Scheme的文学编程文档<shell|Goldfish.tmu>也开源出来，整个项目以开源的方式推进。
从Goldfish Scheme V17.10.8开始，我们确定了Goldfish Scheme的文学编程文档的许可证为<with|font-series|bold|知识共享署名-相同方式共享4.0国际许可协议>。
本文档是采用中文编写的。在2024年，开源软件项目的文档采用中文编写并不是主流。首先，Goldfish Scheme项目的前三位作者的母语都是中文，采用母语作为文档的语言是自然而然的；其次，在大模型时代，计算机辅助翻译已经非常成熟且廉价，我们相信中文文档不会是Goldfish Scheme走向世界的阻碍。
<section|许可证>
本文档采用文学编程方式编写，Goldfish Scheme相关的所有代码几乎都包含在本文档中。本文档的许可证分为代码和文档两部分，其中代码部分采用Apache许可证，相关信息在每一个源代码文件的头部都会显式声明，未显式声明的源代码默认采用Apache许可证；其中文档部分采用<with|font-series|bold|知识共享署名-相同方式共享4.0国际许可协议>授权。您可以自由地分享、修改本作品，只要您遵循以下条件：
<\description>
<item*|署名>您必须给出适当的署名，提供作品的链接，并指明是否有任何变更。您可以以任何合理的方式做这些事，但不得以任何方式暗示许可人赞同您或您的使用。
<item*|相同方式共享>如果您再混合、转换或基于本作品创作，您必须以相同的许可协议发布其成果。
</description>
Goldfish Scheme是浙江三鲤网络科技有限公司发起的开源项目，我们在分发源代码时，版权信息统一采用The Goldfish Scheme Authors作为Goldfish Scheme的作者。那么谁是The Goldfish Scheme Authors呢？这些信息我们会在Goldfish Scheme的仓库的根目录下的<shell|AUTHORS>文件中维护：
<\verbatim-chunk|AUTHORS|false|false>
# The original authors of the SRFI reference IMPL are kept in indivisual files
# This AUTHORS file is for The Goldfish Scheme Authors.
#
# Names should be added to this file like so:
# Name or Organization \<less\>email address\<gtr\>
\;
Liii Network Inc. \<less\>*@liii.pro\<gtr\>
沈达 \<less\>[email protected]\<gtr\>
刘念 \<less\>[email protected]\<gtr\>
Yifan Lu \<less\>[email protected]\<gtr\>
\;
Yansong Li \<less\>[email protected]\<gtr\>
Leiyu He \<less\>[email protected]\<gtr\>
Duolei Wang \<less\>[email protected]\<gtr\>
Yingyao Zhou \<less\>[email protected]\<gtr\>
赵淑婷 \<less\>[email protected]\<gtr\>
Shen Wei \<less\>[email protected]\<gtr\>
Noctis Zhang \<less\>[email protected]\<gtr\>
Andy Yu \<less\>[email protected]\<gtr\>
邢思宇 \<less\>[email protected]\<gtr\>
Jiayi Dong \<less\>[email protected]\<gtr\>
Yancheng Li \<less\>[email protected]\<gtr\>
Xinyi Yu \<less\>[email protected]\<gtr\>
\;
</verbatim-chunk>
我们会联系Goldfish Scheme的贡献者，更新<shell|AUTHORS>文件。Goldfish Scheme的贡献者并不一定在这个文件中，有可能我们没有及时更新，也有可能相关贡献者希望保持匿名。
<section|相关机构>
支持Goldfish Scheme的相关机构如下所示：
<\itemize>
<item>浙江三鲤网络科技有限公司
<item>中国科学技术大学-德清阿尔法创新研究院
</itemize>
<chapter|(liii base)><label|chapter:liii_base>
\;
Goldfish Scheme解释器默认会加载<scm|(liii base)>。如果不想默认加载<scm|(liii base)>，请使用s7、r7rs或者sicp模式。
<scm|(liii base)>由以下函数库组成：
<\description>
<item*|(scheme base)>由R7RS定义的Scheme基础函数库
<item*|(srfi srfi-2)>由SRFI-2定义的<scm|and-let*>
<item*|(srfi srfi-8)>由SRFI-8定义的<scm|receive>
<item*|(liii base)>三鲤扩展函数和S7内置的非R7RS函数，例如<scm|display*>
</description>
<section|许可证>
<\goldfish-chunk|goldfish/scheme/base.scm|false|true>
;
; Copyright (C) 2024 The Goldfish Scheme Authors
;
; Licensed under the Apache License, Version 2.0 (the "License");
; you may not use this file except in compliance with the License.
; You may obtain a copy of the License at
;
; http://www.apache.org/licenses/LICENSE-2.0
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
; WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
; License for the specific language governing permissions and limitations
; under the License.
;
\;
</goldfish-chunk>
<\goldfish-chunk|goldfish/liii/base.scm|false|true>
;
; Copyright (C) 2024 The Goldfish Scheme Authors
;
; Licensed under the Apache License, Version 2.0 (the "License");
; you may not use this file except in compliance with the License.
; You may obtain a copy of the License at
;
; http://www.apache.org/licenses/LICENSE-2.0
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
; WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
; License for the specific language governing permissions and limitations
; under the License.
;
\;
</goldfish-chunk>
\;
<\scm-chunk|tests/goldfish/liii/base-test.scm|false|true>
;
; Copyright (C) 2024 The Goldfish Scheme Authors
;
; Licensed under the Apache License, Version 2.0 (the "License");
; you may not use this file except in compliance with the License.
; You may obtain a copy of the License at
;
; http://www.apache.org/licenses/LICENSE-2.0
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
; WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
; License for the specific language governing permissions and limitations
; under the License.
;
\;
</scm-chunk>
<section|接口>
<\scm-chunk|goldfish/scheme/base.scm|true|true>
(define-library (scheme base)
(export
\ \ let-values
\ \ ; R7RS 5: Program Structure
\ \ define-values define-record-type
\ \ ; R7RS 6.2: Numbers
\ \ square exact inexact max min floor s7-floor ceiling s7-ceiling truncate s7-truncate
\ \ round s7-round floor-quotient gcd lcm s7-lcm boolean=? exact-integer-sqrt
\ \ ; R7RS 6.4: list
\ \ pair? cons car cdr set-car! set-cdr! caar cadr cdar cddr
\ \ null? list? make-list list length append reverse list-tail
\ \ list-ref list-set! memq memv member assq assv assoc list-copy
\ \ ; R7RS 6.5: Symbol
\ \ symbol? symbol=? string-\<gtr\>symbol symbol-\<gtr\>string
\ \ ; R7RS 6.6: Characters
\ \ digit-value
\ \ ; R7RS 6.7: String
\ \ string-copy
\ \ ; R7RS 6.8: Vector
\ \ vector-\<gtr\>string string-\<gtr\>vector vector-copy vector-copy! vector-fill!
\ \ ; R7RS 6.9: Bytevectors
\ \ bytevector? make-bytevector bytevector bytevector-length bytevector-u8-ref
\ \ bytevector-u8-set! bytevector-copy bytevector-append
\ \ utf8-\<gtr\>string string-\<gtr\>utf8 u8-string-length bytevector-advance-u8
\ \ ; Input and Output
\ \ call-with-port port? binary-port? textual-port? input-port-open? output-port-open?
\ \ open-binary-input-file open-binary-output-file close-port eof-object
\ \ ; Control flow
\ \ string-map vector-map string-for-each vector-for-each
\ \ ; Exception
\ \ raise guard read-error? file-error?)
(begin
\;
</scm-chunk>
<\goldfish-chunk|goldfish/liii/base.scm|true|true>
(define-library (liii base)
(import (scheme base)
\ \ \ \ \ \ \ \ (srfi srfi-2)
\ \ \ \ \ \ \ \ (srfi srfi-8))
(export
\ \ ; (scheme base) defined by R7RS
\ \ let-values
\ \ ; R7RS 5: Program Structure
\ \ define-values define-record-type
\ \ ; R7RS 6.2: Numbers
\ \ square exact inexact max min floor s7-floor ceiling s7-ceiling truncate s7-truncate
\ \ round s7-round floor-quotient gcd lcm s7-lcm exact-integer-sqrt
\ \ ; R7RS 6.3: Booleans
\ \ boolean=?
\ \ ; R7RS 6.4: list
\ \ pair? cons car cdr set-car! set-cdr! caar cadr cdar cddr
\ \ null? list? make-list list length append reverse list-tail
\ \ list-ref list-set! memq memv member assq assv assoc list-copy
\ \ ; R7RS 6.5: Symbol
\ \ symbol? symbol=? string-\<gtr\>symbol symbol-\<gtr\>string
\ \ ; R7RS 6.6: Characters
\ \ digit-value
\ \ ; R7RS 6.7: String
\ \ string-copy
\ \ ; R7RS 6.8 Vector
\ \ vector-\<gtr\>string string-\<gtr\>vector vector-copy vector-copy! vector-fill!
\ \ ; R7RS 6.9 Bytevectors
\ \ bytevector? make-bytevector bytevector bytevector-length bytevector-u8-ref
\ \ bytevector-u8-set! bytevector-copy bytevector-append
\ \ utf8-\<gtr\>string string-\<gtr\>utf8 u8-string-length u8-substring bytevector-advance-u8
\ \ ; Input and Output
\ \ call-with-port port? binary-port? textual-port? input-port-open? output-port-open?
\ \ open-binary-input-file open-binary-output-file close-port eof-object
\ \ ; Control flow
\ \ string-map vector-map string-for-each vector-for-each
\ \ ; Exception
\ \ raise guard read-error? file-error?
\ \ ; SRFI-2
\ \ and-let*
\ \ ; SRFI-8
\ \ receive
\ \ ; Extra routines
\ \ loose-car loose-cdr in? compose identity any?
\ \ ; Extra structure
\ \ let1 \ typed-lambda typed-define
)
(begin
\;
</goldfish-chunk>
<section|测试>
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(import (liii check)
\ \ \ \ \ \ \ \ (liii base)
\ \ \ \ \ \ \ \ (liii list)
\ \ \ \ \ \ \ \ (liii case)
\ \ \ \ \ \ \ \ (liii lang))
\;
(check-set-mode! 'report-failed)
\;
</scm-chunk>
<section|表达式>
本节对应R7RS的第四节：表达式。
<subsection|原语表达式>
原语表达式可以分为：变量、字面量、函数的应用、匿名函数、分支表达式、赋值表达式、文件包含表达式。
<paragraph|lambda>
<paragraph|quote>
<paragraph|if>
测试 if 语句的真、假分支，使用简单表达式
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (if (\<gtr\> 3 2) 3 2) =\<gtr\> 3)
(check (if (\<less\> 3 2) 3 2) =\<gtr\> 2)
\;
</scm-chunk>
\;
测试 if 语句的真、假分支，使用复杂表达式
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (if (and (\<gtr\> 3 1) (\<less\> 3 4)) 'true-branch 'false-branch) =\<gtr\> 'true-branch)
(check (if (or (\<gtr\> 3 4) (\<less\> 3 1)) 'true-branch 'false-branch) =\<gtr\> 'false-branch)
\;
</scm-chunk>
<paragraph|set!>
<paragraph|include>
<paragraph|include-ci>
\;
<subsection|派生表达式>
<paragraph|cond>
验证cond表达式的行为
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (cond ((\<gtr\> 3 2) 3) (else 2)) =\<gtr\> 3)
(check (cond ((\<less\> 3 2) 3) (else 2)) =\<gtr\> 2)
(check (cond ((and (\<gtr\> 3 1) (\<less\> 3 4)) 'true-branch) (else 'false-branch)) =\<gtr\> 'true-branch)
(check (cond ((or (\<gtr\> 3 4) (\<less\> 3 1)) 'true-branch) (else 'false-branch)) =\<gtr\> 'false-branch)
\;
</scm-chunk>
测试cond与lambda结合
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (cond (2 =\<gtr\> (lambda (n) (* n 2)))) =\<gtr\> 4)
(check (cond (#f =\<gtr\> (lambda (n) (* n 2))) (else 'no-match)) =\<gtr\> 'no-match)
(check (cond (3 =\<gtr\> (lambda (n) (* n 2))) (else 'no-match)) =\<gtr\> 6)
\;
</scm-chunk>
<value|r7rs><paragraph|case><index|case>
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (case '+
\ \ \ \ \ \ \ \ \ ((+ -) 'p0)
\ \ \ \ \ \ \ \ \ ((* /) 'p1))
\ \ =\<gtr\> 'p0)
\;
(check (case '-
\ \ \ \ \ \ \ \ \ ((+ -) 'p0)
\ \ \ \ \ \ \ \ \ ((* /) 'p1))
\ \ =\<gtr\> 'p0)
\;
(check (case '*
\ \ \ \ \ \ \ \ \ ((+ -) 'p0)
\ \ \ \ \ \ \ \ \ ((* /) 'p1))
\ \ =\<gtr\> 'p1)
\;
(check (case '@
\ \ \ \ \ \ \ \ \ ((+ -) 'p0)
\ \ \ \ \ \ \ \ \ ((* /) 'p1))
\ \ =\<gtr\> #\<less\>unspecified\<gtr\>)
\;
(check (case '&
\ \ \ \ \ \ \ \ \ ((+ -) 'p0)
\ \ \ \ \ \ \ \ \ ((* /) 'p1))
\ \ =\<gtr\> #\<less\>unspecified\<gtr\>)
\;
</scm-chunk>
<value|r7rs><paragraph|and><index|and>
检查 <code*|and> 是否正确处理多个布尔表达式。
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check-true (and #t #t #t))
(check-false (and #t #f #t))
(check-false (and #f #t #f))
(check-false (and #f #f #f))
\;
</scm-chunk>
验证当 <code*|and> 没有参数时的行为。
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check-true (and))
\;
</scm-chunk>
测试 <code*|and> 与混合类型参数的组合。
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check-true (and 1 '() "non-empty" #t))
(check-false (and #f '() "non-empty" #t))
(check-false (and 1 '() "non-empty" #f))
\;
</scm-chunk>
检查 <code*|and> 在复合表达式中的行为。
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check-true (and (\<gtr\> 5 3) (\<less\> 5 10)))
(check-false (and (\<gtr\> 5 3) (\<gtr\> 5 10)))
\;
</scm-chunk>
验证 <code*|and> 的短路行为。
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check-catch 'error-name
\ \ (and (error 'error-name "This should not be evaluated") #f))
(check-false (and #f (error "This should not be evaluated")))
\;
</scm-chunk>
验证and返回值非布尔值的情况。
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (and #t 1) =\<gtr\> 1)
\;
</scm-chunk>
<value|r7rs><paragraph|or><index|or>
<value|r7rs><paragraph|when><index|when>
测试 when 中条件为真的情况
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (when #t 1) =\<gtr\> 1)
\;
</scm-chunk>
测试 when 中条件为假的情况
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (when #f 1 ) =\<gtr\> #\<less\>unspecified\<gtr\>)
\;
</scm-chunk>
\;
测试when中添加简单条件为真的情况
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (when (\<gtr\> 3 1) 1 ) =\<gtr\> 1)
\;
</scm-chunk>
测试when中添加简单条件为假的情况
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (when (\<gtr\> 1 3) 1 ) =\<gtr\> #\<less\>unspecified\<gtr\>)
\;
</scm-chunk>
<value|r7rs><paragraph|unless><index|unless>
<value|r7rs><paragraph|let> <index|let>
let 是 Scheme 中用于局部变量绑定的语法结构。它允许在某个作用域内定义一组局部变量，并在该作用域内使用这些变量。let 表达式的特点是所有变量的初始值表达式是并行计算的，因此变量之间不能相互引用。
let 的语法：
\;
(let ((var1 init1) (var2 init2) ...)
\ \ body)
\;
<\itemize-minus>
<item>var1, var2, ... ：局部变量的名称。
<item>init1, init2, ... ：每个变量的初始值表达式。
<item>body：let 表达式的主体部分，可以包含多个表达式。body 中的表达式会按顺序执行，最后一个表达式的值作为整个 let 表达式的返回值
</itemize-minus>
\;
let 的特点：
<\enumerate>
<item>并行绑定：
所有变量的初始值表达式是并行计算的。
变量的初始值表达式不能引用其他在 let 中定义的变量。
<item>作用域：
变量的作用域仅限于 let 表达式的 body 部分。
在 body 中，变量可以被多次使用或修改。
<item>返回值：
let 表达式的返回值是 body 中最后一个表达式的值。
</enumerate>
\;
测试基本的let绑定
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let ((x 1)) x) =\<gtr\> 1)
\;
</scm-chunk>
测试多个变量绑定
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let ((x 1) (y 2)) (+ x y)) =\<gtr\> 3)
\;
</scm-chunk>
测试let的作用域
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let ((x 1))
\ \ \ \ \ \ \ \ \ (let ((x 2))
\ \ \ \ \ \ \ \ \ \ \ x)) =\<gtr\> 2)
\;
</scm-chunk>
测试let与if结合
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let ((x 1))
\ \ \ \ \ \ \ \ \ (if (\<gtr\> x 0)
\ \ \ \ \ \ \ \ \ \ \ \ \ x
\ \ \ \ \ \ \ \ \ \ \ \ \ -x)) =\<gtr\> 1)
\;
</scm-chunk>
named let 是 Scheme 中的一种特殊形式的 let，它允许在 let 表达式中定义一个递归函数。named let 的语法如下：
\;
(let name ((var1 init1) (var2 init2) ...)
\ \ body)
\;
测试 named let 的基本功能
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let loop ((n 5) (acc 0))
\ \ \ \ \ \ \ \ \ (if (zero? n)
\ \ \ \ \ \ \ \ \ \ \ acc
\ \ \ \ \ \ \ \ \ \ \ (loop (- n 1) (+ acc n)))) =\<gtr\> 15)
\;
</scm-chunk>
测试 named let 的递归功能
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let factorial ((n 5))
\ \ \ \ \ \ \ \ \ (if (= n 1)
\ \ \ \ \ \ \ \ \ \ \ 1
\ \ \ \ \ \ \ \ \ \ \ (* n (factorial (- n 1))))) =\<gtr\> 120)
\;
</scm-chunk>
测试 named let 的多参数情况
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let sum ((a 3) (b 4))
\ \ \ \ \ \ \ \ \ (+ a b)) =\<gtr\> 7)
\;
</scm-chunk>
测试 named let 的嵌套使用
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let outer ((x 2))
\ \ \ \ \ \ \ \ \ (let inner ((y 3))
\ \ \ \ \ \ \ \ \ \ \ (+ x y))) =\<gtr\> 5)
\;
</scm-chunk>
\;
<value|r7rs><paragraph|let*><index|let*>
<value|r7rs><paragraph|letrec>
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(define (test-letrec)
\ \ (letrec ((even?
\ \ \ \ \ \ \ \ \ \ \ \ \ (lambda (n)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (if (= n 0)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ #t
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (odd? (- n 1)))))
\ \ \ \ \ \ \ \ \ \ \ \ (odd?
\ \ \ \ \ \ \ \ \ \ \ \ \ (lambda (n)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (if (= n 0)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ #f
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (even? (- n 1))))))
\ \ \ \ (list (even? 10) (odd? 10))))
\;
(check (test-letrec) =\<gtr\> (list #t #f))
\;
(check-catch 'wrong-type-arg
\ \ (letrec ((a 1) (b (+ a 1))) (list a b)))
\;
</scm-chunk>
<value|r7rs><paragraph|letrec*><index|letrec*>
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check
\ \ (letrec* ((a 1) (b (+ a 1))) (list a b))
\ \ =\<gtr\> (list 1 2))
\;
</scm-chunk>
\;
<value|r7rs><paragraph|let-values><index|let-values>
<\scm-chunk|goldfish/scheme/base.scm|true|true>
; 0-clause BSD
; Bill Schottstaedt
; from S7 source repo: r7rs.scm
(define-macro (let-values vars . body)
\ \ (if (and (pair? vars)
\ \ \ \ \ \ \ \ \ \ \ (pair? (car vars))
\ \ \ \ \ \ \ \ \ \ \ (null? (cdar vars)))
\ \ \ \ \ \ `((lambda ,(caar vars)
\ \ \ \ \ \ \ \ \ \ ,@body)
\ \ \ \ \ \ \ \ ,(cadar vars))
\ \ \ \ \ \ `(with-let
\ \ \ \ \ \ \ \ (apply sublet (curlet)
\ \ \ \ \ \ \ \ \ \ (list
\ \ \ \ \ \ \ \ \ \ \ \ ,@(map
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (lambda (v)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ `((lambda ,(car v)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (values ,@(map (lambda (name)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (values (symbol-\<gtr\>keyword name) name))
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (let args-\<gtr\>proper-list ((args (car v)))
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (cond ((symbol? args)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (list args))
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ((not (pair? args))
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ args)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ((pair? (car args))
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (cons (caar args)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (args-\<gtr\>proper-list (cdr args))))
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (else
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (cons (car args)
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (args-\<gtr\>proper-list (cdr args)))))))))
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ,(cadr v)))
\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ vars)))
\ \ \ \ \ \ \ \ ,@body)))
\;
</scm-chunk>
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (let-values (((ret) (+ 1 2))) (+ ret 4)) =\<gtr\> 7)
(check (let-values (((a b) (values 3 4))) (+ a b)) =\<gtr\> 7)
\;
</scm-chunk>
<value|r7rs><paragraph|let*-values>
<paragraph|and-let*><index|and-let*>
<\scm-chunk|tests/goldfish/liii/base-test.scm|true|true>
(check (and-let* ((hi 3) (ho #f)) (+ hi 1)) =\<gtr\> #f)
(check (and-let* ((hi 3) (ho #t)) (+ hi 1)) =\<gtr\> 4)
\;
</scm-chunk>
<subparagraph|SRFI>
<\scm-chunk|goldfish/srfi/srfi-2.scm|false|false>
; 0-clause BSD by Bill Schottstaedt from S7 source repo: s7test.scm
(define-library (srfi srfi-2)
(export and-let*)
(begin
\;
(define-macro (and-let* vars . body)
\ \ `(let () (and ,@(map (lambda (v) `(define ,@v)) vars) (begin ,@body))))
\;
) ; end of begin
) ; end of define-library
\;
</scm-chunk>