Module

Wasm.String

Package: purescript-wasm-base
Repository: purs-wasm/purescript-wasm-base

The first-order, byte-level $Str primitives the higher-level Data.String.* code-point operations are built on. A String is a UTF-8 byte array; these expose it as bytes — the Rust .as_bytes() / .bytes() analog — so the code-point layer (length / charAt / take / …, written as PureScript that decodes UTF-8) can run standalone on wasm and can be specialized by purs-wasm optimizer.

"Code unit = byte" lives here, deliberately NOT in Data.String.CodeUnits (which adopts code-point semantics on this backend; ADR 0030). The foreign imports resolve to intrinsics on the wasm backend (Intrinsics.qualifiedIntrinsic — Wasm.String.*); the accompanying Wasm/String.js provides them for stock purs / purs-backend-es so a wasm-base-using project also compiles and runs on the JS backends (there a "byte" is a UTF-16 code unit — the JS-side encoding — which is correct for JS-hosted code).

#byteLength Source

byteLength :: String -> Int

The UTF-8 byte length. On wasm: the StrLen intrinsic (array.len on the $Bytes).

#byteAt Source

byteAt :: String -> Int -> Int

The byte (0-255) at index i, unchecked (out of range traps). On wasm: the StrByteAt intrinsic (array.get on the $Bytes).

#unsafeNew Source

unsafeNew :: Int -> String

Allocate a String of n zeroed bytes, to be filled with unsafeSetByte. On wasm: the StrNew intrinsic (a zeroed $Str).

#unsafeSetByte Source

unsafeSetByte :: String -> Int -> Int -> String

Write byte b (0-255) at index i, mutating the string in place, and return that same string, so a builder loop threads it — keeping the write live (not dead-code-eliminated) and ordered by the data dependency, without needing an effect. Unchecked (out of range traps). On wasm: the StrSetByte intrinsic (array.set, then yields the string).

Modules: Wasm.Array; Wasm.Boolean; Wasm.Char; Wasm.Int; Wasm.String