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Closes #1547 , which was caused by misspelled/nonexistent types being interpreted as type variables. In #1550 I proposed one solution to the problem, namely, to stop implicitly quantifying types and require explicit `forall` on any polymorphic type. This PR represents an alternative solution: to keep implicit quantification but require all types to start with an uppercase letter, as in Haskell. I think I like this one better but I'm open to feedback. Specifically, with this PR: - All built-in type constructors (`Int`, `Cmd`, `Unit`, etc.) must start with a capital letter - Type variables: - Must start with a lowercase letter or underscore - May not be named a lowercase version of a type constructor, *e.g.* `int` - This is important so that old code with lowercase types is not silently accepted by parsing the former types as implicitly quantified type variables; even in cases where old code no longer typechecks, this will give better error messages. - Term variables: - May start with upper- or lowercase - May be named lowercase versions of type names, *e.g.* `let f : Int -> Int = \int. int + 1` is fine This PR obviously represents a bigger breaking change. Once we merge this we might consider adding an option to `swarm format` to be able to parse old code with lowercase types and then reformat it with uppercase, to aid in porting code. Once this is merged I will also regenerate the wiki pages that mention types. Closes #1550.
27 lines
1003 B
XML
27 lines
1003 B
XML
def cons : a * b -> (a -> b) -> (a -> b) = \p. \k. \a.
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if (a == fst p) {snd p} {k a}
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end
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def nil : a -> Cmd Unit = \a. return () end
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// Suitable to use as e.g.
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// installKeyHandler "(S-)←↓↑→ [Del] [g]rab [h]arvest [d]rill [s]can [b]locked [u]pload" pilot
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def pilot : Key -> Cmd Unit =
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cons (key "Up", move) $
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cons (key "Down", turn back) $
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cons (key "Left", turn left) $
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cons (key "Right", turn right) $
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cons (key "S-Up", turn north) $
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cons (key "S-Down", turn south) $
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cons (key "S-Left", turn west) $
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cons (key "S-Right", turn east) $
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cons (key "Del", selfdestruct) $
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cons (key "g", res <- grab; log res) $
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cons (key "h", res <- harvest; log res) $
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cons (key "d", res <- drill forward; case res (\_. return ()) log) $
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cons (key "s", res <- scan forward; case res (\_. return ()) log) $
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cons (key "b", b <- blocked; if b {log "blocked"} {log "not blocked"}) $
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cons (key "u", upload base) $
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nil
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end
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