8a96fde229
Remark: the termination proofs are commented because Lean 4 is currently ignoring them and accepting non-terminating functions. These files are based on an experiment implemented using Lean 3. We can find it here: https://gist.github.com/leodemoura/f5d82426c105b5fae0880e77024f6e9c We will use coroutines to implement the interaction between reader, elaborator and main driver.
59 lines
1.3 KiB
Text
59 lines
1.3 KiB
Text
import init.control.coroutine
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import system.io
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universes u v
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open coroutine
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namespace ex1
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inductive tree (α : Type u)
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| leaf {} : tree
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| node : tree → α → tree → tree
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/-- Coroutine as generators/iterators -/
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def visit {α : Type v} : tree α → coroutine unit α unit
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| tree.leaf := pure ()
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| (tree.node l a r) := do
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visit l,
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yield a,
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visit r
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def tst {α : Type} [has_to_string α] (t : tree α) : io unit :=
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do c ← pure $ visit t,
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(yielded v₁ c) ← pure $ resume c (),
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(yielded v₂ c) ← pure $ resume c (),
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io.print_ln $ to_string v₁,
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io.print_ln $ to_string v₂,
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return ()
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#eval tst (tree.node (tree.node (tree.node tree.leaf 5 tree.leaf) 10 (tree.node tree.leaf 20 tree.leaf)) 30 tree.leaf)
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end ex1
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namespace ex2
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def ex : state_t nat (coroutine nat string) unit :=
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do
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x ← read,
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y ← get,
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put (y+5),
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yield ("1) val: " ++ to_string (x+y)),
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x ← read,
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y ← get,
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yield ("2) val: " ++ to_string (x+y)),
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return ()
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def tst2 : io unit :=
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do let c := state_t.run ex 5,
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(yielded r c₁) ← pure $ resume c 10,
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io.print_ln r,
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(yielded r c₂) ← pure $ resume c₁ 20,
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io.print_ln r,
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(done _) ← pure $ resume c₂ 30,
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(yielded r c₃) ← pure $ resume c₁ 100,
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io.print_ln r,
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io.print_ln "done",
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return ()
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#eval tst2
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end ex2
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