When comparing Swift vs Pyret, the Slant community recommends Swift for most people. In the question“What is the best programming language to learn first?” Swift is ranked 30th while Pyret is ranked 41st.
Ranked in these QuestionsQuestion Ranking
Pro Modern syntax
Pro Swift is closer to other platforms
Apple’s modern programming language is easier to understand for non-iOS developers and minimizes time for additional explanations and clarifications. Moreover, Swift can be used as a script language. It is an interesting solution for the iOS community to unify writing of build scripts. At the time being iOS developers are split up in regard to this activity. Some of them write build scripts in Bash, others use Ruby, Python, etc. Swift gives an amazing opportunity to be applied to all iOS programming needs.
More details can be found here https://mlsdev.com/blog/51-7-advantages-of-using-swift-over-objective-c
Pro Works with Apple's Cocoa and Cocoa Touch frameworks
Pro Can be used as a Just-In-Time language
Pro Inherent parallelism
Pro Low memory footprint due to reference counting
Pro Backed by Apple
Pro Performance speed comparable to native C
Pro Swift has some clever tricks up its sleeve
Due to having elements of a functional programming language. Things like 'map' and 'filter' for example.
Pro Uses LLVM compiler and Obj-C runtime allowing C, Objective-C, Objective-C++ and Swift code to run side by side within a single program
Pro Online IDE
You can use the development environment without installation in your browser and share your programs via the Google Drive integration.
Pro Designed for education
A primary goal of Pyret is to be an excellent choice for a first programming language. This heavily influences the development of the language. For example: if it's felt that some aspect of the language could be made better for the language's users, The development team won't hesitate about implementing breaking (non backwards compatible) changes into Pyret for the greater good of the language. This makes Pyret an impressively "wart free" programming language.
Con Swift is a moving target
They've released 1.2 so far, and 2.0 is coming soon. Every small update brings adjustments to paradigms (such as how to do type casting) that can be a little frustrating to absorb. Objective C was also constantly updating, however, but not at the same rate these days.
Con Missing IDE features
For example: content assist, go to declaration, etc.