Prompt Blocks in Sesi

A prompt block is Sesi's string composition primitive. It lets you assemble a named string from literals and variables — similar to template literals in other languages — without concatenation operators.

---

Declaration

prompt := 'prompt' identifier '{' content '}'
content := (string | expression)*

Place string literals and variable names sequentially inside the braces. Sesi joins them automatically:

let name    = "Ada"
let version = "1.9.0"

prompt header {"Welcome to Sesi "version". Hello, "name}

header now holds the composed string "Welcome to Sesi 1.9.0. Hello, Ada".

Rule: Raw newlines between elements (outside of a string literal) inside { } are a syntax error — they are treated as statement separators. Newlines that live inside a string literal are fine.

---

Printing a Prompt

A prompt block is a value. Pass it to show like any other variable:

let lang = "Sesi"
let ver  = "1.9.0"

prompt title {"Welcome to "lang ver}

show title   // Welcome to Sesi 1.9.0

---

Using a Prompt as a String

Prompts resolve to plain strings and can be used anywhere a string is expected:

let user = "Ada"

prompt greeting {"Hello, "user". Glad you're here."}

write_file("welcome.txt", greeting)

---

Multiline Content

A literal newline inside a string literal spans the prompt across lines:

let name  = "Ada"
let score = 98

prompt report {"Student: "name"
Score: "score"
Grade: A"}

show report
// Student: Ada
// Score: 98
// Grade: A

---

Composing Prompts from Other Prompts

A prompt can reference another prompt by name, building up complex strings in layers:

let first = "Ada "
let last  = "Lovelace"

prompt fullName {first last}
prompt badge {"[Developer] "fullName}

show badge   // [Developer] Ada Lovelace

---

Prompts vs. + Concatenation

Both produce the same result. Prefer prompt blocks for readability when combining several pieces:

let name = "Ada"
let role = "admin"

// Using +
let line1 = "User: " + name + " | Role: " + role

// Using prompt
prompt line2 {"User: "name" | Role: "role}

Preferred: Avoid + inside show statements and prompt blocks. Sequential placement is idiomatic Sesi.

---

Quick Reference

// Declare
prompt title {"Hello, "name" — version "version}

// Print directly
show title

// Use as a string value
write_file("out.txt", title)

// Multiline newlines inside string literals
prompt report {"Name: "name"
Score: "score}

// Compose from other prompts
prompt full  {first last}
prompt badge {"[Admin] "full}

---