[mbakke]

The sister comment appears to be somewhat confused. The "virality" of GPL is that if you "link" a GPL program then your license must be compatible and the combination as a whole becomes GPL. Importing a library may count as a derived work/linking.

The LGPL was created to avoid this limitation and is a natural choice for programming languages and interpreters.

As an example, GNU Guile, an interpreter for the Scheme language, is LGPL licensed. Writing any nontrivial Scheme script requires importing code from Guile. If it was GPL then all scripts had to be GPL compatible; but since it's LGPL, programs using Guile modules can have any license (even proprietary).