45 lines
950 B
Markdown
45 lines
950 B
Markdown
# Expressions
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_Expressions_ are the basis of programming in Ava. An expression is some code
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that will produce a _value_ when evaluated.
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## Syntax
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Most non-[Definition](definitions.md) code is considered an expression.
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Expressions include:
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- Literals
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- Variables
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- Function Calls
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- Control Expressions
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In general, using a Literal or a Variable for an expression wraps that value in
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a `pure` function that returns the value when evaluated.
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## Control Expressions
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### If Then
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The `if/then` expression expects an expression that returns a _Boolean Value_.
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That expression is evaluated. If it evaluates to `true`, the `then` expression
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is evaluated. Otherwise the `else` expression is evaluated.
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```
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if <boolean expr> then <expr> else <expr>
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```
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### Do Yield
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TODO: This is incomplete
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The `do/yield` expression allows for imperative composition of monadic
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expressions.
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```
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do
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x <- foo()
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y <- bar()
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_ <- baz()
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yield
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x + y
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```
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