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:PROPERTIES:
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:ID: 0e092b64-dcaf-4579-9de8-0da3ede9dc53
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:END:
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#+title: Side Effects
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In [[id:9e68d422-cced-4177-96d1-90f777b9a493][Software Development]], the effects of running a function or bit of code
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outside of its local environment. Examples include reaching out over the network
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to talk to a database, reading or writing a file on disk, or printing some
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output. This contrasts with [[id:ec68f43a-7c63-4e22-81f9-b119791a6dd1][Purity]], where such effects are not allowed.
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Effectful code has implicit, rather than explicit, state. This is to say, the
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behavior of the code may differ not based solely on its explicit inputs, but
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also values at a higher level of scope, the stability of the network, or the
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current contents of a file. They may also impact external state, which can make
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them difficult to reason about and sensitive to the order in which statements
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are executed.
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