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| -rw-r--r-- | txr.1 | 23 |
1 files changed, 23 insertions, 0 deletions
@@ -40784,6 +40784,25 @@ and is processed accordingly. Similarly, is equivalent to .codn "@(@y (dwim f @x))" . +The dot position of +.meta avar +in the predicate syntax denotes function application. So that is to say, the +pattern predicate form +.code "(f . @a)" +where +.code @a +is in the dotted position invokes the function +.code f +as if by evaluation of the form +.code "(f . x)" +where +.code x +is hidden temporary variable holding the object corresponding to the pattern. +The form +.code "(f . x)" +is a standard \*(TL notation with the same meaning as +.codn "(apply (fun f) x)" . + .TP* Examples: .verb @@ -40804,6 +40823,10 @@ is equivalent to (let ((h #H(() (a 1) (b 2)))) (when-match @(@y [h @x]) 'a (list x y))) -> (a 1) + + ;; apply (1 2 3) to < using dot position + (when-match @(@x (< . @sym)) '(1 2 3) (list x sym)) + - > (t (1 2 3)) .brev .coNP Macros @ when-match and @ if-match |