Re:Why Fennel?
by munificent on Wednesday September 13, 2023 @02:04PM
(#37499663)
Caveat: I haven't used Fennel but just inferring from what makes sense...
The Lua VM that they compile to already handles missing arguments with some attendant but unavoidable performance cost.
Fennel's own `lambda` form that they layer on top does check for missing arguments, but it must do so by generating extra Lua code to do those checks. That additional code has a runtime cost.
Using `fn` avoids that extra generated code and its cost.
If Fennel had its own runtime and VM, then the performance story for how missing arguments are handled would be different.
The Lua VM that they compile to already handles missing arguments with some attendant but unavoidable performance cost.
Fennel's own `lambda` form that they layer on top does check for missing arguments, but it must do so by generating extra Lua code to do those checks. That additional code has a runtime cost.
Using `fn` avoids that extra generated code and its cost.
If Fennel had its own runtime and VM, then the performance story for how missing arguments are handled would be different.