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iace

Translation status: English reader-locale proof. Code fences render through the en pipeline; prose is canonical Latin.

Throws a recoverable error.

Syntax: iace <expression>

Category#

errors

Examples#

radix/corpus/iace/iace-si-guard.fab (canonical · keyword)#

Conditional throw with si guard.

# =============================================================================
# iace — Conditional throw with si guard
# =============================================================================
#
# What this teaches:
#   • Conditional throw with si guard.
#   • Related keywords: cape, mori, si, ⇥
#
# Common mistakes:
#   • Using `iace si` without a `⇥` on the enclosing function or a `fac/cape` wrapper — the guard sugar expands to `si cond { iace val }`, which still needs an error context.
#
# See also: cape, mori, si, ⇥
# =============================================================================

# iace with optional si guard
#
# iace <value> [si <condicio>]
#
# GRAMMAR:
#   throwStmt :← 'iace' expr ['si' expr]
#
# The optional `si` guard is parser sugar:
#   iace val si cond  →  si cond { iace val }
#
# Without the guard, iace is unconditional (unchanged).
#
# EXPECTED OUTPUT:
#   "ok: valid input"
#   "caught: empty input"
#   "caught: negative"

fn validata(string input) → string ⇥ string {
    # Guard: throw if input is empty
    throw "empty input" if input.longitudo() ≡ 0

    return "valid: §"(input)
}

main {
    # Happy path — guard not triggered
    do {
        const string a ← validata("hello")
        print "ok: §"(a)
    }
    catch err {
        print "unexpected: §"(err)
    }

    # Empty input — iace si guard triggers
    do {
        const string b ← validata("")
        print "should not reach"
    }
    catch err {
        print "caught: §"(err)
    }

    # iace with si on same line
    do {
        throw "force throw" if true
        print "should not reach"
    }
    catch err {
        print "caught: §"(err)
    }
}

radix/corpus/iace/iace.fab (canonical · keyword)#

Throws a recoverable error.

# =============================================================================
# iace — Throws a recoverable error
# =============================================================================
#
# What this teaches:
#   • Throws a recoverable error.
#   • Related keywords: ⇥, cape, mori, redde
#
# Common mistakes:
#   • Using `iace` without a `⇥` on the enclosing function or a `fac { ... } cape err { ... }` wrapper — `iace` requires an error-handling context (SEM010).
#
# See also: ⇥, cape, mori, redde
# =============================================================================

# iace — recoverable throw and cape handler
#
# iace <value>
# fac { <body> }
# cape err { <handler> }
#
# GRAMMAR:
#   throwStmt :← 'iace' expr
#   facStmt   :← 'fac' block catchClause?
#
# EXPECTED OUTPUT:
#   Caught error messages from fac/cape recovery paths.
#
# BACKEND:
#   Rust/Go lowering does not emit iace/cape yet — compile-only smoke.

main {
    # Bare iace with textus payload
    do {
        throw "Something went wrong"
    }
    catch err {
        print "Caught:", err
    }

    # iace with interpolated message
    const _ code ← 404
    do {
        throw "Error code: §"(code)
    }
    catch err {
        print "Caught:", err
    }

    # Conditional iace inside fac — validation guard
    const _ value ← -5
    do {
        if value < 0 {
            throw "Value must be non-negative"
        }
        print "Value is valid"
    }
    catch err {
        print "Validation failed:", err
    }
}

Expected output:

Caught: Something went wrong
Caught: Error code: 404
Validation failed: Value must be non-negative