SLIME has fancy commands for compiling functions, files, and packages. The fancy part is that notes and warnings offered by the Lisp compiler are intercepted and annotated directly onto the corresponding expressions in the Lisp source buffer. (Give it a try to see what this means.)
With (positive) prefix argument the form is compiled with maximal debug settings (C-u C-c C-c). With negative prefix argument it is compiled for speed (M-- C-c C-c). If a numeric argument is passed set debug or speed settings to it depending on its sign.
The code for the region is executed after compilation. In principle,
the command writes the region to a file, compiles that file, and loads
the resulting code.
With (positive) prefix argument the file is compiled with maximal
debug settings (C-u C-c C-k). With negative prefix argument it is compiled for
speed (M-- C-c C-k). If a numeric argument is passed set debug or speed settings
to it depending on its sign.
The annotations are indicated as underlining on source forms. The compiler message associated with an annotation can be read either by placing the mouse over the text or with the selection commands below.