--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/StaticDicts/StaticDicts.jl	Fri Mar 19 16:40:30 2021 +0100
@@ -0,0 +1,82 @@
+module StaticDicts
+
+export StaticDict
+
+"""
+    StaticDict{K,V,N} <: AbstractDict{K,V}
+
+A static dictionary implementing the interface for an `AbstractDict`. A
+`StaticDict` is fully immutable and after creation no changes can be made.
+
+The immutable nature means that `StaticDict` can be compared with `===`, in
+constrast to regular `Dict` or `ImmutableDict` which can not. (See
+https://github.com/JuliaLang/julia/issues/4648 for details) One important
+aspect of this is that `StaticDict` can be used in a struct while still
+allowing the struct to be comared using the default implementation of `==` for
+structs.
+
+Lookups are done by linear search.
+
+Duplicate keys are not allowed and an error will be thrown if they are passed
+to the constructor.
+"""
+struct StaticDict{K,V,N} <: AbstractDict{K,V}
+    pairs::NTuple{N,Pair{K,V}}
+
+    function StaticDict{K,V}(pairs::Vararg{Pair,N}) where {K,V,N}
+        if !allunique(first.(pairs))
+            throw(DomainError(pairs, "keys must be unique"))
+        end
+        return new{K,V,N}(pairs)
+    end
+end
+
+function StaticDict(pairs::Vararg{Pair})
+    K = typejoin(firsttype.(pairs)...)
+    V = typejoin(secondtype.(pairs)...)
+    return StaticDict{K,V}(pairs...)
+end
+
+StaticDict(pairs::NTuple{N,Pair} where N) = StaticDict(pairs...)
+
+function Base.get(d::StaticDict, key, default)
+    for p ∈ d.pairs
+        if key == p.first
+            return p.second
+        end
+    end
+
+    return default
+end
+
+Base.iterate(d::StaticDict) = iterate(d.pairs)
+Base.iterate(d::StaticDict, state) = iterate(d.pairs,state)
+Base.length(d::StaticDict) = length(d.pairs)
+
+
+"""
+    merge(d1::StaticDict, d2::StaticDict)
+
+Merge two `StaticDict`. Repeating keys is considered and error. This may
+change in a future version.
+"""
+function Base.merge(d1::StaticDict, d2::StaticDict)
+    return StaticDict(d1.pairs..., d2.pairs...)
+end
+
+
+"""
+    firsttype(::Pair{T1,T2})
+
+The type of the first element in the pair.
+"""
+firsttype(::Pair{T1,T2}) where {T1,T2} = T1
+
+"""
+    secondtype(::Pair{T1,T2})
+
+The type of the secondtype element in the pair.
+"""
+secondtype(::Pair{T1,T2}) where {T1,T2}  = T2
+
+end # module