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effect-extras

StringX overview

Generic, framework-agnostic extensions to Effect’s String module.

Added in v0.0.0

Table of contents

combinators

ensurePrepend

Prepends start to string_ unless string_ already starts with it.

Idempotent: applying it to an already-prefixed string is a no-op, so ensurePrepend("foofoo", "foo") stays "foofoo" rather than gaining a second "foo".

Signature

export declare const ensurePrepend: ((start: string) => (string_: string) => string) &
  ((string_: string, start: string) => string)

Example

import { pipe } from "effect"
import { StringX } from "@nunofyobiz/effect-extras"

// data-first — adds the prefix when missing
assert.deepStrictEqual(StringX.ensurePrepend("bar", "foo"), "foobar")

// idempotent — already prefixed, returned unchanged
assert.deepStrictEqual(StringX.ensurePrepend("foobar", "foo"), "foobar")

// data-last (piped)
assert.deepStrictEqual(pipe("bar", StringX.ensurePrepend("foo")), "foobar")

Added in v0.0.0

insertBeforeLine

Inserts lines immediately before the line at anchorIndex, preserving the anchor line and everything after it; returns the rejoined string.

content is split on \n and lines are spliced in just before the zero-based anchorIndex. An anchorIndex of 0 prepends, and one at or past the end appends.

Signature

export declare const insertBeforeLine: ((
  anchorIndex: number,
  lines: readonly string[]
) => (content: string) => string) &
  ((content: string, anchorIndex: number, lines: readonly string[]) => string)

Example

import { pipe } from "effect"
import { StringX } from "@nunofyobiz/effect-extras"

// data-first — insert before line 1, keeping the anchor and the rest
assert.deepStrictEqual(StringX.insertBeforeLine("a\nb\nc", 1, ["X"]), "a\nX\nb\nc")

// an anchor at the end appends
assert.deepStrictEqual(StringX.insertBeforeLine("a\nb", 2, ["X"]), "a\nb\nX")

// data-last (piped)
assert.deepStrictEqual(pipe("a\nb", StringX.insertBeforeLine(0, ["X"])), "X\na\nb")

Added in v0.0.0

prepend

Prepends start to string_.

v4’s String module has no native prepend (only concat), so this fills the gap as a pipeable helper.

Signature

export declare const prepend: ((start: string) => (string_: string) => string) &
  ((string_: string, start: string) => string)

Example

import { pipe } from "effect"
import { StringX } from "@nunofyobiz/effect-extras"

// data-first
assert.deepStrictEqual(StringX.prepend("world", "hello "), "hello world")

// data-last (piped)
assert.deepStrictEqual(pipe("world", StringX.prepend("hello ")), "hello world")

Added in v0.0.0

replaceLineRange

Replaces the inclusive line range [startLine, endLine] of content with replacement lines, returning the rejoined string.

content is split on \n; the zero-based lines startLine through endLine (both inclusive) are dropped and replacement is spliced into their place. Pass an empty replacement to delete the range. Indices clamp naturally via Array.take/Array.drop, so out-of-range values don’t throw.

Signature

export declare const replaceLineRange: ((
  startLine: number,
  endLine: number,
  replacement: readonly string[]
) => (content: string) => string) &
  ((content: string, startLine: number, endLine: number, replacement: readonly string[]) => string)

Example

import { pipe } from "effect"
import { StringX } from "@nunofyobiz/effect-extras"

// data-first — replace lines 1..2 with a single line
assert.deepStrictEqual(StringX.replaceLineRange("a\nb\nc\nd", 1, 2, ["X"]), "a\nX\nd")

// an empty replacement deletes the range
assert.deepStrictEqual(StringX.replaceLineRange("a\nb\nc\nd", 1, 2, []), "a\nd")

// data-last (piped)
assert.deepStrictEqual(pipe("a\nb\nc", StringX.replaceLineRange(1, 1, ["X", "Y"])), "a\nX\nY\nc")

Added in v0.0.0

surround

Wraps string_ between start and end.

No v4 native equivalent — handy for quoting, bracketing, or fencing a value.

Signature

export declare const surround: ((start: string, end: string) => (string_: string) => string) &
  ((string_: string, start: string, end: string) => string)

Example

import { pipe } from "effect"
import { StringX } from "@nunofyobiz/effect-extras"

// data-first
assert.deepStrictEqual(StringX.surround("value", "[", "]"), "[value]")

// data-last (piped)
assert.deepStrictEqual(pipe("value", StringX.surround("(", ")")), "(value)")

Added in v0.0.0