61 lines
1.6 KiB
Go
61 lines
1.6 KiB
Go
// Package saccharine defines the AST for the Saccharine language, a sugared
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// lambda calculus with let bindings and multi-statement clauses.
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package saccharine
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// An Expression is a node in the Saccharine abstract syntax tree.
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// It is a sealed interface; only types in this package may implement it.
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type Expression interface {
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expression()
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}
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// An Abstraction is a lambda expression with zero or more parameters.
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// A zero-parameter abstraction is treated as a thunk.
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type Abstraction struct {
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Parameters []string
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Body Expression
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}
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// An Application applies an expression to zero or more arguments.
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type Application struct {
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Abstraction Expression
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Arguments []Expression
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}
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// An Atom is a named variable.
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type Atom struct {
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Name string
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}
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// A Clause is a sequence of statements followed by a return expression.
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type Clause struct {
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Statements []Statement
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Returns Expression
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}
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func (Abstraction) expression() {}
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func (Application) expression() {}
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func (Atom) expression() {}
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func (Clause) expression() {}
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// A Statement is a declaration within a Clause.
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// It is a sealed interface; only types in this package may implement it.
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type Statement interface {
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statement()
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}
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// A LetStatement binds a name (with optional parameters) to an expression.
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type LetStatement struct {
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Name string
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Parameters []string
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Body Expression
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}
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// A DeclareStatement evaluates an expression for its side effects within a
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// clause.
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type DeclareStatement struct {
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Value Expression
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}
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func (LetStatement) statement() {}
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func (DeclareStatement) statement() {}
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