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| -rw-r--r-- | gtwiwtg.lisp | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/gtwiwtg.lisp b/gtwiwtg.lisp index 5e954ee..ca7e605 100644 --- a/gtwiwtg.lisp +++ b/gtwiwtg.lisp @@ -630,15 +630,75 @@ Caveat: (filter! (complement pred) gen2)))) (defun intersperse! (gen1 gen2 &rest gens) + "Produces a generator that intersperses one value from each of its +argument generators, one after the other, until any of those +generators run out of values. + +Examples: + +> (intersperse! (seq '(:name :job :hobbies)) + (seq '(\"buckaroo banzai\" + \"rocker\" + (\"neuroscience\" + \"particle physics\" + \"flying fighter jets\")))) + +> (collect *) + + (:NAME \"buckaroo banzai\" :JOB \"rocker\" :HOBBIES + (\"neuroscience\" \"particle physics\" \"flying fighter jets\")) + +> (intersperse! (times 5) (repeater 'a 'b 'c) (range :by -10)) + +> (collect *) + + (0 A 0 1 B -10 2 C -20 3 A -30 4 B -40) + " (inflate! #'seq (apply #'zip! gen1 gen2 gens))) (defun truncate! (n gen) + "Shrinks a generator to generate a series of at most N values." (map! #'first (zip! gen (times n)))) (defun inject! (fn gen) + "Injects an effect into a generator. Use this to add a side-effect +to the value generation process. The new generator produces exactly +the same values as GEN. + +Possibly good for debugging. + +Example: + +> (map! #'reverse + (inejct! #'print ; look at values before they're reversed + (zip! (range) + (repeater :cool :beans) + (seq \"banzai!\")))) + +> (collect *) + + (0 :COOL #\b) ;these are printed to stdout + (1 :BEANS #\a) + (2 :COOL #\n) + (3 :BEANS #\z) + (4 :COOL #\a) + (5 :BEANS #\i) + + ((#\b :COOL 0) (#\a :BEANS 1) (#\n :COOL 2) (#\z :BEANS 3) (#\a :COOL 4) + (#\i :BEANS 5)) + +" (map! (lambda (x) (funcall fn x) x) gen)) (defun disperse! (n gen) + "Produces a list of N gnerators, G1,...,GN. + +G1 produces every Nth value of GEN, including first value. +G2 produces every Nth+1 value of GEN, including the second value. +... +GN produces every Nth + (N-1) value of GEN, including the (N-1)th value. + +This is sort of the opposite of INTERSPERSE!." (loop :for i :below n :for cloned :in (nfurcate! n gen) |