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ba13f5ca60
Since 0.101.0 we will finally catch more illegal `def` signatures. As the grammar for input/output types is rather restricted, this would error otherwise
53 lines
1.7 KiB
Text
53 lines
1.7 KiB
Text
# Trampoline module to allow for recursion functions that won't stack overflow.
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# The tramp create command is to be used to return a closure that will perform
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# the trampoline iteration. This closure can then be passed to some other
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# command that will execute it for its own purposes.
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# The tramp test command is one such command that will create the closure
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# and then directly run it. It can be used to test your recursive functions
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# that return thunks or terminating values.
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# Returns a closure that when called will iterate over the returned thunks
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# from the function being trampolined. Must initially call the function
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# which must return either a thunk or a terminating value.
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export def create [thunk: any] {
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return {||
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mut $inner_thunk = $thunk
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while ($inner_thunk | describe) == closure {
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$inner_thunk = (do $inner_thunk)
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}
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$inner_thunk
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}
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}
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# Will run the trampoline closure whichis created # by performing a call to 'tramp create' withthe value of val.
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# The parameter val must be either a terminating value or closure, which will get run until
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# the terminating value is returned from the current closure which
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# is returned from this function.
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export def test [val: any]: nothing -> any {
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let cl = (create $val)
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do $cl
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}
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# For those cases where you do not want to first create a trampoline closure
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# but just want to run the recursive command directly.
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# Example usage
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# use tramp.nu
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# source even-odd.nu
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# tramp recurse (odd 9876543)
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# true
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# Explicitly bounces the trampoline over a recursive function without first
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# creating a closure .
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export def recurse [val: any]: nothing -> any {
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mut maybe_thunk = $val
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while ($maybe_thunk | describe) == closure {
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$maybe_thunk = (do $maybe_thunk)
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}
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$maybe_thunk
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}
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