d0f2da214b
* Clarify the documentation of foldl': That the arguments are forced before application (?) of `op` is necessarily true. What is important to stress is that we force every application of `op`, even when the value turns out to be unused. * Move the example before the comment about strictness to make it less confusing: It is a general example and doesn't really showcase anything about foldl' strictness. * Add test cases which nail down aspects of foldl' strictness: * The initial accumulator value is not forced unconditionally. * Applications of op are forced. * The list elements are not forced unconditionally.
10 lines
201 B
Nix
10 lines
201 B
Nix
# Tests that the rhs argument of op is not forced unconditionally
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let
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lst = builtins.foldl'
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(acc: x: acc ++ [ x ])
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[ ]
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[ 42 (throw "this shouldn't be evaluated") ];
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in
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builtins.head lst
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