@lang:bytes.concat

Concatenate bytes values together.

On-chain (@lang:bytes.concat!): Up to 4 parts may be live calls, the rest hex constants; each live part past the first is re-resolved by every later offset.

Returns: bytes

Syntax

@lang:bytes.concat(first ...rest)

Arguments

Name	Type	Description
`first`	`bytes`	First bytes value
`[...rest]`	`bytes`	Bytes values to append

On-chain face (@bytes.concat!)

Concatenate bytes values on-chain through Operators.concat: constant hex parts and live call parts.

Up to four parts may be live. The envelopes splice into the calldata in order at the end, and each offset after the first live part is itself a live word: the constant base plus the running total of the earlier payloads, rounded up to whole words. A part may still sit at any logical position, since its ABI offset points at the splice rather than at where it reads.

Four is a hard limit rather than a guideline. An operand expression is a tree with no way to name a subterm, so each live part is re-resolved by every offset that follows it — source call included — which is N(N-1)/2 extra resolutions and a calldata blob growing with the square. An assertion is judged inside an eth_call, so an over-budget expression runs out of gas and reverts, and a reverted judge cannot be told apart from one that legitimately failed. Better to refuse at build time.

Examples

load lang

set $oracle 0x44fA8E6f47987339850636F88629646662444217

assert @bytes.concat!(0x1234 $oracle::{blob()(bytes)}) == 0xabcd