tricu

A lazy functional language based on Tree Calculus
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migration.tri (1396B)

      1 !import bd2c14d6db6b69308a5252a8e839705a55d30e815f012900b094315263e08d81 *
      2 !import 3f70d95cf1bae0928ee89acd2a9e0cdd8287796efae32a9f08d33e3dd0149c55 *
      3 !export v1
      4 !export v2
      5 
      6 -- Archived profile v0: [name email]. v1: adds schemaVersion and displayName.
      7 -- v2: also supplies marketingOptIn=false; existing data is preserved.
      8 -- Try result = v1 ["James" "james@example.org"].
      9 -- Change v1 to v2 to compare the two target schemas.
     10 -- A migration receipt can record the input identity, executable hash/export,
     11 -- output identity and wire schema. Running this demo stays entirely local.
     12 -- Records use [fieldName tag value]: 0 = text, 1 = natural, 2 = Boolean.
     13 -- Base supplies arithmetic/Booleans; hostString? checks Unicode scalar text.
     14 
     15 failure message = [["status" 0 "error"] ["message" 0 message]]
     16 
     17 migrate version name email = case and? (hostString? name) (hostString? email) of
     18   ^true = case version of
     19     1 = [["schemaVersion" 1 1] ["displayName" 0 name] ["email" 0 email]]
     20     _ = [["schemaVersion" 1 2] ["displayName" 0 name] ["email" 0 email]
     21       ["marketingOptIn" 2 false]]
     22   _ = failure "Name and email must be scalar text."
     23 
     24 profile _ (t _) = failure "Expected a list."
     25 profile _ [_ | (t _)] = failure "Expected a list."
     26 profile version [name email] = migrate version name email
     27 profile _ _ = failure "Expected [name email]."
     28 
     29 v1 values = profile 1 values
     30 v2 values = profile 2 values