pop, drop & get with basic range feature for stringlist

doc/specs/stdlib_stringlist_type.md

@@ -421,7 +421,7 @@ program demo_equality_operator
   res = ( stringlist == ["#4", "#3", "#2", "#1"] )
     ! res <-- .true.
 
-  print'(a)', stringlist == ["#4", "#3", "#1"]
+  print'(l0)', stringlist == ["#4", "#3", "#1"]
     ! .false.
 
 end program demo_equality_operator
@@ -491,7 +491,7 @@ program demo_inequality_operator
   res = ( stringlist /= ["#111", "#222", "#333", "#444"] )
     ! res <-- .true.
 
-  print'(a)', stringlist /= ["#4", "#3", "#1"]
+  print'(l0)', stringlist /= ["#4", "#3", "#1"]
     ! .true.
 
 end program demo_inequality_operator

doc/specs/stdlib_strings.md

@@ -146,8 +146,8 @@ The result is of scalar logical type.
 program demo
   use stdlib_strings, only : starts_with
   implicit none
-  print'(a)', starts_with("pattern", "pat")  ! T
-  print'(a)', starts_with("pattern", "ern")  ! F
+  print'(l0)', starts_with("pattern", "pat")  ! T
+  print'(l0)', starts_with("pattern", "ern")  ! F
 end program demo
 ```
 
@@ -188,8 +188,8 @@ The result is of scalar logical type.
 program demo
   use stdlib_strings, only : ends_with
   implicit none
-  print'(a)', ends_with("pattern", "ern")  ! T
-  print'(a)', ends_with("pattern", "pat")  ! F
+  print'(l0)', ends_with("pattern", "ern")  ! T
+  print'(l0)', ends_with("pattern", "pat")  ! F
 end program demo
 ```
 

src/stdlib_string_type.fypp

@@ -678,7 +678,7 @@ contains
 
     !> Moves the allocated character scalar from 'from' to 'to'
     !> No output
-    subroutine move_string_string(from, to)
+    pure subroutine move_string_string(from, to)
         type(string_type), intent(inout) :: from
         type(string_type), intent(out) :: to
 
@@ -688,7 +688,7 @@ contains
 
     !> Moves the allocated character scalar from 'from' to 'to'
     !> No output
-    subroutine move_string_char(from, to)
+    pure subroutine move_string_char(from, to)
         type(string_type), intent(inout) :: from
         character(len=:), intent(out), allocatable :: to
 
@@ -698,7 +698,7 @@ contains
 
     !> Moves the allocated character scalar from 'from' to 'to'
     !> No output
-    subroutine move_char_string(from, to)
+    pure subroutine move_char_string(from, to)
         character(len=:), intent(inout), allocatable :: from
         type(string_type), intent(out) :: to
 
@@ -708,7 +708,7 @@ contains
 
     !> Moves the allocated character scalar from 'from' to 'to'
     !> No output
-    subroutine move_char_char(from, to)
+    pure subroutine move_char_char(from, to)
         character(len=:), intent(inout), allocatable :: from
         character(len=:), intent(out), allocatable :: to