Joseph Ferano
a4c6b996ff
The trio the author decided on 2026-09-20 is now all built: def is CL's defparameter — its initialiser runs on every daemon re-run, unguarded, so an edited initialiser repaints the same storage on C-c C-c plus re-run — defonce (Clojure's name for CL's defvar, per the author) initialises once behind the .init~once. flag, and defconst stays the image. One parse arm reads both forms; the difference is Ast.reinit, carried to Tast.global's grerun. Emit.startup_plan gives a def no guard flag, and Check.check_global lifts every def initialiser — zero and literal included — into global/<n>, so the host's startup reaches it through the function cell and a re-evaluated def swaps it (Session's def_inits; Emit.redefinition declares the cell for a non-sibling target). The old defvar spelling is refused with the rename and both compiling spellings, and every program, test, doc and editor list is swept — except sand.flan, the author's live WIP, whose seven defvar lines are flagged in FIX.org and keep its three dependent tests red on this branch.
89 lines
3.2 KiB
Plaintext
89 lines
3.2 KiB
Plaintext
;; Function values, the non-escaping kind: a code address and no environment
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;; beside it. Capture does not exist, so nothing here can outlive anything.
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;;
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;; This is a Lisp-1 — one top-level namespace, enforced — so a bare function
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;; name *is* the function and there is no #' to write.
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(defn double [x i32] i32 (* x 2))
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(defn negate [x i32] i32 (- 0 x))
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(defn square [x i32] i32 (* x x))
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;; The shape map/filter/reduce want: the function arrives as a parameter, is
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;; called, and is never stored.
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(defn each [xs [i32] f (Fn [i32] i32)] ()
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(dotimes [i (len xs)]
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(set (at xs i) (f (at xs i)))))
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(defn fold [xs [i32] f (Fn [i32] i32)] i32
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(let [t 0]
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(dotimes [i (len xs)]
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(set t (+ t (f (at xs i)))))
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t))
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;; A comparator, which is the other half of what was blocked: a sort that is
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;; told the order rather than having it written in. Insertion sort, because the
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;; point here is the parameter and not the algorithm.
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(defn insertion-by [xs [i32] before? (Fn [i32 i32] bool)] ()
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(dotimes [i (len xs)]
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(let [j i]
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(while (and (> j 0) (before? (at xs j) (at xs (- j 1))))
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(swap xs j (- j 1))
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(set j (- j 1))))))
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(defn ascending [a i32 b i32] bool (< a b))
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(defn descending [a i32 b i32] bool (> a b))
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;; Returning one. A function value is a link-time constant with no environment,
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;; so handing it back up is no different from handing it down.
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(defn pick [up bool] (Fn [i32 i32] bool)
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(if up ascending descending))
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;; A function value calling another, and the transfer channel crossing an
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;; indirect call: a callee reached by pointer signals exactly as one reached by
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;; name, and the handler is established across the call.
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(defstruct TooBig [n i32])
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(defn checked [x i32] i32
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(when (> x 100) (signal (TooBig {.n x})))
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x)
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(defonce seen i32)
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;; A handler-bind and an fn literal in *one* function, which is the case that
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;; would catch the two lifted-function name sequences sharing a counter: both
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;; are lifted out of [handles] and both are numbered within it.
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(defn handles [] ()
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(handler-bind [(TooBig [c] (set seen (+ seen (.n c))))]
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(let [xs [5 200 7 300]]
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(println (fold (slice xs 0 4) checked))
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(println (fold (slice xs 0 4) (fn [x] (min x 10))))))
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(print "seen ") (print seen) (println ""))
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(defn main [] i32
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(let [xs [1 2 3 4]]
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;; A name in value position, passed down.
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(each (slice xs 0 4) double)
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(print (at xs 0)) (print " ") (print (at xs 3)) (println "")
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;; 2 + 4 + 6 + 8 negated
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(println (fold (slice xs 0 4) negate))
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;; An fn literal, whose parameter types come from the position it is in.
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(println (fold (slice xs 0 4) (fn [x] (+ x 1))))
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;; A let binding of function type, called by the name it is bound to.
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(let [f square]
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(println (f 9))))
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;; A comparator, and the same slice sorted both ways.
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(let [ys [3 1 4 1 5 9 2 6]
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s (slice ys 0 8)]
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(insertion-by s ascending)
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(print (at s 0)) (print " ") (print (at s 7)) (println "")
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(insertion-by s descending)
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(print (at s 0)) (print " ") (print (at s 7)) (println "")
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;; A returned function value, and a computed head calling it.
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(insertion-by s (pick true))
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(print (at s 0)) (println "")
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(println ((pick false) 1 2)))
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(handles)
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0)
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