Block Expression

Syntax

block_expr ::=  '{' statement* [ expr ] '}'
             | '@{' statement* [ expr ] '}'

A block expression consists of zero or more statements enclosed with a pair of braces. Optionally, a block expression may end with an Expression. Additionally, a block expression may start with @.

Typing

The type of a block expression is the type of expr. Note that the type of expr may be <no-return>. If expr is elidid the type is unit: ().

Semantics

All item statements within a block exrpression’s statement list are bound. This is similar to a letrec in functional languages. Then, all statements consecutively evaluate. Finally, the closing expr (if present) evaluates. This is the evaluation of the whole block expression. If expr is elided, unit () is yielded.

Examples

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