Async Block

AsyncBlockExpression represents an asynchronous code block. When compiled, it automatically generates a IAsyncStateMachine state machine that executes AwaitExpression nodes asynchronously, suspending and resuming across await points.

The block returns Task (for void result) or Task<T> (when the last expression produces a value).

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Factory Methods

using static Hyperbee.Expressions.ExpressionExtensions;

Overload	Description
BlockAsync( params Expression[] expressions )	Block with no local variables
BlockAsync( ParameterExpression[] variables, params Expression[] expressions )	Block with local variables
BlockAsync( Expression[] expressions, ExpressionRuntimeOptions options )	Block with runtime options
BlockAsync( ParameterExpression[] variables, Expression[] expressions, ExpressionRuntimeOptions options )	Block with variables and options

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Usage

Basic Async Block

using static System.Linq.Expressions.Expression;
using static Hyperbee.Expressions.ExpressionExtensions;

// An async block that awaits two tasks and returns the sum
var a = Variable( typeof(int), "a" );
var b = Variable( typeof(int), "b" );

var asyncBlock = BlockAsync(
    [a, b],
    Assign( a, Await( Constant( Task.FromResult( 10 ) ) ) ),
    Assign( b, Await( Constant( Task.FromResult( 32 ) ) ) ),
    Add( a, b )   // return value: Task<int> with value 42
);

var lambda = Lambda<Func<Task<int>>>( asyncBlock );
var fn = lambda.Compile();
var result = await fn();  // result == 42

Void Async Block

// A void async block: returns Task (no result value)
var asyncBlock = BlockAsync(
    Await( Call( typeof(Task).GetMethod("Delay", [typeof(int)]), Constant( 100 ) ) ),
    Call( typeof(Console).GetMethod("WriteLine", [typeof(string)]), Constant( "done" ) )
);

var lambda = Lambda<Func<Task>>( asyncBlock );
var fn = lambda.Compile();
await fn();

Using with Compiler Options

var options = new ExpressionRuntimeOptions { Optimize = true };

var asyncBlock = BlockAsync(
    [a],
    Assign( a, Await( someTask ) ),
    a,
    options
);

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Type

The Type property returns Task when the last expression in the block is void, or Task<T> when the last expression produces a value of type T.

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Notes

• AwaitExpression nodes must appear directly inside an AsyncBlockExpression. Awaiting outside an async block is not supported.
• Variables declared in the block are hoisted to state machine fields to survive suspension points.
• Nested AsyncBlockExpression blocks are supported – each generates its own state machine.
• See ExpressionRuntimeOptions for configuration options.
• See Await for the Await factory method.