diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 32 |
1 files changed, 22 insertions, 10 deletions
@@ -40288,12 +40288,12 @@ as its value. .coNP Pattern operator @ with .synb -.mets @(with >> [ side-pattern | << name ] < expr << main-pattern ) +.mets @(with <> [ main-pattern ] >> { side-pattern | << name } << expr ) .syne .desc The .code with -pattern operator matches the +pattern operator matches the optional .meta main-pattern against a corresponding object, while matching a .meta side-pattern @@ -40303,15 +40303,27 @@ against the value of the expression .meta expr which is embedded in the syntax. +First, if +.meta main-pattern +is present in the syntax, +it is matched its corresponding object. This match must +succeed, or else the +.code with +operator fails to match. -First, +Next, .meta expr -is evaluated in the scope of earlier pattern variables. It is unspecified -whether later pattern variables are visible. The matching of +is evaluated in the scope of earlier pattern variables, including any +which that emanate from +.metn main-pattern . +It is unspecified +whether later pattern variables are visible. + +Finally, .meta side-pattern -follows, and if that succeeds, then the matching of -.meta main-pattern -against the corresponding object takes place. +is matched against the value of +.metn expr . +If that succeeds, then the operator has successfully matched. If a .meta name @@ -40323,11 +40335,11 @@ it must be a bindable symbol or else .TP* Examples: .verb - (when-match (@(with x 42 @a) @b @c) '(1 2 3) (list a b c x)) + (when-match (@(with @a x 42) @b @c) '(1 2 3) (list a b c x)) --> (1 2 3 42) (let ((o 3)) - (when-match (@(evenp x) @(with @(oddp y) o @z)) '(4 6) + (when-match (@(evenp x) @(with @z @(oddp y) o)) '(4 6) (list x y z))) --> (4 3 6) .brev |