Flat

Flat

is an attribute that can be assigned to a symbol f to indicate that all expressions involving nested functions f should be flattened out. This property is accounted for in pattern matching.

Details

  • Flat corresponds to the mathematical property of associativity.
  • For a symbol f with attribute Flat, f[f[a,b],f[c]] is automatically reduced to f[a,b,c].
  • Functions like Plus, Times, and Dot are Flat.
  • For a Flat function f, the variables x and y in the pattern f[x_,y_] can correspond to any sequence of arguments.
  • The Flat attribute must be assigned before defining any values for a Flat function.

Examples

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Basic Examples  (3)

Nested expressions with flat functions are flattened out:

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Flat implements the notion of associativity:

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Flat allows the pattern matcher to use associativity:

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Scope  (3)

Properties & Relations  (5)

Possible Issues  (4)

Introduced in 1988
(1.0)