From 7eeb91b822334b151c5b4a15ce9528a2a655d914 Mon Sep 17 00:00:00 2001 From: Linus Date: Wed, 9 Nov 2022 16:15:18 +0100 Subject: [PATCH] Add internal definitions to derived forms This commit adds internal definitions to the following derived forms: when, unless, cond, case, with-fluids, and and-let*. * doc/ref/api-control.texi (Conditionals): Update the syntax and docs of when, unless, cond, and case. * module/ice-9/and-let-star.scm (and-let*): Changed begins to let. * module/ice-9/boot-9.scm (cond, case, when, unless, with-fluids): Changed begins to let. --- doc/ref/api-control.texi | 25 +++++++++++++------------ module/ice-9/and-let-star.scm | 6 +++--- module/ice-9/boot-9.scm | 12 ++++++------ 3 files changed, 22 insertions(+), 21 deletions(-) diff --git a/doc/ref/api-control.texi b/doc/ref/api-control.texi index 087e795..ece6a60 100644 --- a/doc/ref/api-control.texi +++ b/doc/ref/api-control.texi @@ -152,10 +152,10 @@ documentation: @example (define-syntax-rule (when test stmt stmt* ...) - (if test (begin stmt stmt* ...))) + (if test (let () stmt stmt* ...))) (define-syntax-rule (unless test stmt stmt* ...) - (if (not test) (begin stmt stmt* ...))) + (if (not test) (let () stmt stmt* ...))) @end example That is to say, @code{when} evaluates its consequent statements in order @@ -167,11 +167,11 @@ statements if @var{test} is false. Each @code{cond}-clause must look like this: @lisp -(@var{test} @var{expression} @dots{}) +(@var{test} @var{body} @dots{}) @end lisp -where @var{test} and @var{expression} are arbitrary expressions, or like -this +where @var{test} is an arbitrary expression and @var{body} is a +lambda-like body, or like this @lisp (@var{test} => @var{expression}) @@ -217,7 +217,7 @@ result of the @code{cond}-expression. @var{key} may be any expression, and the @var{clause}s must have the form @lisp -((@var{datum1} @dots{}) @var{expr1} @var{expr2} @dots{}) +((@var{datum1} @dots{}) @var{body} @dots{}) @end lisp or @@ -229,7 +229,7 @@ or and the last @var{clause} may have the form @lisp -(else @var{expr1} @var{expr2} @dots{}) +(else @var{expr1} @var{body} @dots{}) @end lisp or @@ -239,13 +239,14 @@ or @end lisp All @var{datum}s must be distinct. First, @var{key} is evaluated. The -result of this evaluation is compared against all @var{datum} values using -@code{eqv?}. When this comparison succeeds, the expression(s) following -the @var{datum} are evaluated from left to right, returning the value of -the last expression as the result of the @code{case} expression. +result of this evaluation is compared against all @var{datum} values +using @code{eqv?}. When this comparison succeeds, the @var{body} +following the @var{datum} is evaluated like the body of a lambda, +returning the value of the last expression as the result of the +@code{case} expression. If the @var{key} matches no @var{datum} and there is an -@code{else}-clause, the expressions following the @code{else} are +@code{else}-clause, the @var{body} following the @code{else} is evaluated. If there is no such clause, the result of the expression is unspecified. diff --git a/module/ice-9/and-let-star.scm b/module/ice-9/and-let-star.scm index 2d53ff3..9427c17 100644 --- a/module/ice-9/and-let-star.scm +++ b/module/ice-9/and-let-star.scm @@ -53,12 +53,12 @@ ((_ orig-form ((var expr)) . body) (identifier? #'var) #'(let ((var expr)) - (and var (begin . body)))) + (and var (let () . body)))) ((_ orig-form ((expr)) . body) - #'(and expr (begin . body))) + #'(and expr (let () . body))) ((_ orig-form (var) . body) (identifier? #'var) - #'(and var (begin . body))) + #'(and var (let () . body))) ;; Handle bad clauses. ((_ orig-form (bad-clause . rest) . body) diff --git a/module/ice-9/boot-9.scm b/module/ice-9/boot-9.scm index a46145e..dc35370 100644 --- a/module/ice-9/boot-9.scm +++ b/module/ice-9/boot-9.scm @@ -417,10 +417,10 @@ If returning early, return the return value of F." (include-from-path "ice-9/quasisyntax") (define-syntax-rule (when test stmt stmt* ...) - (if test (begin stmt stmt* ...))) + (if test (let () stmt stmt* ...))) (define-syntax-rule (unless test stmt stmt* ...) - (if (not test) (begin stmt stmt* ...))) + (if (not test) (let () stmt stmt* ...))) (define-syntax else (lambda (x) @@ -461,7 +461,7 @@ If returning early, return the return value of F." ((else e e* ...) (lambda (tail) (if (null? tail) - #'((begin e e* ...)) + #'((let () e e* ...)) (bad-clause "else must be the last clause")))) ((else . _) (bad-clause)) ((test => receiver) @@ -488,7 +488,7 @@ If returning early, return the return value of F." ((test e e* ...) (lambda (tail) #`((if test - (begin e e* ...) + (let () e e* ...) #,@tail)))) (_ (bad-clause)))) #'(clause clauses ...)))))))) @@ -534,7 +534,7 @@ If returning early, return the return value of F." ((=> receiver ...) (bad-clause "wrong number of receiver expressions")) - ((e e* ...) #'(begin e e* ...)) + ((e e* ...) #'(let () e e* ...)) (_ (bad-clause))))) (syntax-case #'test (else) ((datums ...) @@ -674,7 +674,7 @@ If returning early, return the return value of F." #`(let ((fluid-tmp fluid) ...) (let ((val-tmp val) ...) #,(emit-with-fluids #'((fluid-tmp val-tmp) ...) - #'(begin exp exp* ...))))))))) + #'(let () exp exp* ...))))))))) (define-syntax current-source-location (lambda (x) -- 2.25.1