Function definition: Difference between revisions

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Functions defined with explicit parameters may be closures, and those defined with implied parameters are not.

Langur functions are first-order. They are pure in terms of setting values, ~~though not~~ in terms of I/O.

Langur functions are first-order. They are pure in terms of setting values and in terms of I/O (unless declared impure).

=== explicit parameters ===

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Operator implied functions are built using an infix operator between curly braces on an f token.

<syntaxhighlight lang="langur">val .multiply = f{x}

.multiply(3, 4)</syntaxhighlight>

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These are built with an infix operator and one operand inside the f{...} tokens.

<syntaxhighlight lang="langur">val .times3 = f{x 3}

map .times3, [1, 2, 3]</syntaxhighlight>

=== impure functions (I/O) ===

Impure functions must be declared as such.

<syntaxhighlight>val .writeit = impure f(.x) { writeln .x }</syntaxhighlight>

Impure functions cannot be passed to pure functions.

=={{header|Lasso}}==