Blam — Better Lua assert messages

blam file.lua file.luau directory

What?

Replaces nonexistent or empty string message arguments of Lua assert calls with the expression being asserted. assert(jump()) becomes assert(jump(), "[blam]\njump()"). Compatible with Lua 5.1, Lua 5.2, Lua 5.3, Lua 5.4, and Luau.

Why?

Often assert messages are meant for developers, not users. assert(#inventory > 0) is about as clear to someone who knows Lua as assert(#inventory > 0, "inventory is empty"). But the default assertion failed! message is useful to nobody, and forces developers to open the file to figure out what's being asserted, even if once they know the assertion, the problem is obviously elsewhere.

assert is even more commonly useful in Luau, where it's used to refine types.

Blam also quiets Selene warnings for assert calls without a message argument.