Joseph Ferano
d6fc15474b
The author: "I think I prefer length over len, because then I'll use len as the variable name". One arm in check.ml, one row in the table beside it, and every (len x) in lib, test, examples, vendor, spike, docs, web, emacs, plan.org and NEXT.md rewritten. Shadowing and builtin/ had already taken most of the sting out: a (defn len ...) was legal and won in its own file, and builtin/len reached past it. What was left is that len was still a builtin — the defn earned a warning, and a wrapper had to say builtin/ at every inner call. Now there is nothing under the short name: len is an ordinary identifier in every position, which is what (let [len (length xs)] ...) wants. length takes over as shadowing's worked example rather than the feature losing one. shadow-builtin.flan, builtin-qualified.flan, pkgs/shadowed and the builtin/ rows in test_flan move to it and go on testing shadowing. A call to a len nothing defines is answered where an unknown function is, after every table and after the shadowing guard, so a program with its own len never reaches it. The sentence is said rather than guessed at — len and length are three edits apart and the did-you-mean's net is one — and the call is written back out through spell_arg, as-slice's spelling lifted out of it and now shared, so what is printed compiles. sand.flan:33 still calls the old name and is the author's to change; until it does, test_acceptance and test_session abort there. Both were run green against a copy with that one line changed. FIX.org says so.
50 lines
2.4 KiB
Plaintext
50 lines
2.4 KiB
Plaintext
;;;; builtin/name: the spelling that always reaches the builtin.
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;;;;
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;;;; Shadowing a builtin is legal and program-wide within the file that does
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;;;; it (shadow-builtin.flan is that rule on its own). What it used to cost
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;;;; was the builtin itself: a (defn length ...) had given up the builtin
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;;;; length for
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;;;; the whole file, so a definition that meant to *wrap* the builtin was
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;;;; unbounded recursion instead, and stack-overflowed at run time with
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;;;; nothing for the compiler to object to.
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;;;;
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;;;; builtin/length is the way out, and it is the package qualifier's own
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;;;; spelling: rl/draw-fps is draw-fps from the package imported as rl, and
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;;;; builtin/length is length from the compiler. builtin is a reserved
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;;;; qualifier —
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;;;; an import may not take it as an alias — so the two can never be confused
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;;;; about which one a name means.
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;;;;
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;;;; Five lines, and between them the whole feature. In order:
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;;;;
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;;;; - 9: (builtin/max 3 9) with nothing in this program named max. The
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;;;; qualifier is legal whether or not anything is shadowed; a spelling that
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;;;; only compiled while some other declaration existed would be a spelling
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;;;; nobody could write down in advance.
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;;;; - 5: this file's own length, which is a real wrapper — it is "1 + the
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;;;; builtin length", and the inner call reaches the builtin rather than
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;;;; itself. This is the program the earlier lane could not write.
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;;;; - 4: builtin/length in the same file, beside the bare name that means the
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;;;; definition. Both spellings, one program, different answers.
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;;;; - 99: the shadowed operator, unchanged. An operator is a builtin like any
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;;;; other and shadows like any other.
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;;;; - 3: builtin/+ — the reader takes builtin/+ as one symbol, because '/'
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;;;; and '+' are both ordinary symbol characters and the token does not
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;;;; begin with a digit or a sign, so an operator needs no exception here.
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;;; The wrapper, written the way the dead end said could not be written: the
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;;; inner builtin/length is the compiler's length, and the outer name is this
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;;; one.
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;;; Both additions are qualified too, since + is shadowed below and this
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;;; function wants the arithmetic and not the 99.
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(defn length [s string] i32 (builtin/+ 1 (builtin/length s)))
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(defn + [a i32 b i32] i32 99)
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(defn main [] ()
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(println (builtin/max 3 9))
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(println (length "abcd"))
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(println (builtin/length "abcd"))
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(println (+ 1 2))
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(println (builtin/+ 1 2)))
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